diff --git a/spec/build_tests_spec.rb b/spec/build_tests_spec.rb
index 3337616..a9fff81 100644
--- a/spec/build_tests_spec.rb
+++ b/spec/build_tests_spec.rb
@@ -82,8 +82,8 @@ describe Rscons do
     Rscons::Environment.new do |env|
       env.Program('simple', Dir['*.c'])
     end
-    File.exists?('simple.o').should be_true
-    `./simple`.should == "This is a simple C program\n"
+    expect(File.exists?('simple.o')).to be_true
+    expect(`./simple`).to eq "This is a simple C program\n"
   end
 
   it 'prints commands as they are executed' do
@@ -92,7 +92,7 @@ describe Rscons do
       env["LD"] = "gcc"
       env.Program('simple', Dir['*.c'])
     end
-    lines.should == [
+    expect(lines).to eq [
       'gcc -c -o simple.o -MMD -MF simple.mf simple.c',
       "gcc -o simple#{env["PROGSUFFIX"]} simple.o",
     ]
@@ -103,7 +103,7 @@ describe Rscons do
     env = Rscons::Environment.new do |env|
       env.Program('header', Dir['*.c'])
     end
-    lines.should == [
+    expect(lines).to eq [
       'CC header.o',
       "LD header#{env["PROGSUFFIX"]}",
     ]
@@ -114,8 +114,8 @@ describe Rscons do
     Rscons::Environment.new do |env|
       env.Program('header', Dir['*.c'])
     end
-    File.exists?('header.o').should be_true
-    `./header`.should == "The value is 2\n"
+    expect(File.exists?('header.o')).to be_true
+    expect(`./header`).to eq "The value is 2\n"
   end
 
   it 'rebuilds a C module when a header it depends on changes' do
@@ -123,10 +123,10 @@ describe Rscons do
     env = Rscons::Environment.new do |env|
       env.Program('header', Dir['*.c'])
     end
-    `./header`.should == "The value is 2\n"
+    expect(`./header`).to eq "The value is 2\n"
     file_sub('header.h') {|line| line.sub(/2/, '5')}
     env.process
-    `./header`.should == "The value is 5\n"
+    expect(`./header`).to eq "The value is 5\n"
   end
 
   it 'does not rebuild a C module when its dependencies have not changed' do
@@ -134,13 +134,13 @@ describe Rscons do
     env = Rscons::Environment.new do |env|
       env.Program('header', Dir['*.c'])
     end
-    `./header`.should == "The value is 2\n"
-    lines.should == [
+    expect(`./header`).to eq "The value is 2\n"
+    expect(lines).to eq [
       'CC header.o',
       "LD header#{env["PROGSUFFIX"]}",
     ]
     env.process
-    lines.should == []
+    expect(lines).to eq []
   end
 
   it "does not rebuild a C module when only the file's timestamp has changed" do
@@ -148,15 +148,15 @@ describe Rscons do
     env = Rscons::Environment.new do |env|
       env.Program('header', Dir['*.c'])
     end
-    `./header`.should == "The value is 2\n"
-    lines.should == [
+    expect(`./header`).to eq "The value is 2\n"
+    expect(lines).to eq [
       'CC header.o',
       "LD header#{env["PROGSUFFIX"]}",
     ]
     sleep 0.05
     file_sub('header.c') {|line| line}
     env.process
-    lines.should == []
+    expect(lines).to eq []
   end
 
   it 're-links a program when the link flags have changed' do
@@ -164,7 +164,7 @@ describe Rscons do
     env = Rscons::Environment.new(echo: :command) do |env|
       env.Program('simple', Dir['*.c'])
     end
-    lines.should == [
+    expect(lines).to eq [
       'gcc -c -o simple.o -MMD -MF simple.mf simple.c',
       "gcc -o simple#{env["PROGSUFFIX"]} simple.o",
     ]
@@ -172,7 +172,7 @@ describe Rscons do
       env["LIBPATH"] += ["libdir"]
       env.Program('simple', Dir['*.c'])
     end
-    lines.should == ["gcc -o simple#{env["PROGSUFFIX"]} simple.o -Llibdir"]
+    expect(lines).to eq ["gcc -o simple#{env["PROGSUFFIX"]} simple.o -Llibdir"]
   end
 
   it 'builds object files in a different build directory' do
@@ -182,9 +182,9 @@ describe Rscons do
       env.build_dir(%r{^src/([^/]+)/}, 'build_\\1/')
       env.Program('build_dir', Dir['src/**/*.c'])
     end
-    `./build_dir`.should == "Hello from two()\n"
-    File.exists?('build_one/one.o').should be_true
-    File.exists?('build_two/two.o').should be_true
+    expect(`./build_dir`).to eq "Hello from two()\n"
+    expect(File.exists?('build_one/one.o')).to be_true
+    expect(File.exists?('build_two/two.o')).to be_true
   end
 
   it 'uses build directories before build root' do
@@ -195,7 +195,7 @@ describe Rscons do
       env.build_root = "build_root"
       env.Program('build_dir', Dir['src/**/*.c'])
     end
-    lines.should == ["CC build/one/one.o", "CC build/two/two.o", "LD build_dir#{env["PROGSUFFIX"]}"]
+    expect(lines).to eq ["CC build/one/one.o", "CC build/two/two.o", "LD build_dir#{env["PROGSUFFIX"]}"]
   end
 
   it 'uses build_root if no build directories match' do
@@ -206,7 +206,7 @@ describe Rscons do
       env.build_root = "build_root"
       env.Program('build_dir.exe', Dir['src/**/*.c'])
     end
-    lines.should == ["CC build_root/src/one/one.o", "CC build_root/src/two/two.o", "LD build_dir.exe"]
+    expect(lines).to eq ["CC build_root/src/one/one.o", "CC build_root/src/two/two.o", "LD build_dir.exe"]
   end
 
   it "expands target and source paths starting with ^/ to be relative to the build root" do
@@ -219,7 +219,7 @@ describe Rscons do
       env.Object("^/one.o", "^/one.c")
       env.Program('build_dir', Dir['src/**/*.c'] + ["^/one.o"])
     end
-    lines.should == [
+    expect(lines).to eq [
       %q{gcc -c -o build_root/one.o -MMD -MF build_root/one.mf -Isrc/one/ -Isrc/two/ build_root/one.c},
       %q{gcc -c -o build_root/src/two/two.o -MMD -MF build_root/src/two/two.mf -Isrc/one/ -Isrc/two/ src/two/two.c},
       %Q{gcc -o build_dir#{env["PROGSUFFIX"]} build_root/src/two/two.o build_root/one.o},
@@ -233,15 +233,15 @@ describe Rscons do
       env.build_dir(%r{^src/([^/]+)/}, 'build_\\1/')
       env.Program('build_dir', Dir['src/**/*.c'])
     end
-    `./build_dir`.should == "Hello from two()\n"
-    File.exists?('build_one/one.o').should be_true
-    File.exists?('build_two/two.o').should be_true
+    expect(`./build_dir`).to eq "Hello from two()\n"
+    expect(File.exists?('build_one/one.o')).to be_true
+    expect(File.exists?('build_two/two.o')).to be_true
     Rscons.clean
-    File.exists?('build_one/one.o').should be_false
-    File.exists?('build_two/two.o').should be_false
-    File.exists?('build_one').should be_false
-    File.exists?('build_two').should be_false
-    File.exists?('src/one/one.c').should be_true
+    expect(File.exists?('build_one/one.o')).to be_false
+    expect(File.exists?('build_two/two.o')).to be_false
+    expect(File.exists?('build_one')).to be_false
+    expect(File.exists?('build_two')).to be_false
+    expect(File.exists?('src/one/one.c')).to be_true
   end
 
   it 'does not clean created directories if other non-rscons-generated files reside there' do
@@ -251,16 +251,16 @@ describe Rscons do
       env.build_dir(%r{^src/([^/]+)/}, 'build_\\1/')
       env.Program('build_dir', Dir['src/**/*.c'])
     end
-    `./build_dir`.should == "Hello from two()\n"
-    File.exists?('build_one/one.o').should be_true
-    File.exists?('build_two/two.o').should be_true
+    expect(`./build_dir`).to eq "Hello from two()\n"
+    expect(File.exists?('build_one/one.o')).to be_true
+    expect(File.exists?('build_two/two.o')).to be_true
     File.open('build_two/tmp', 'w') { |fh| fh.puts "dum" }
     Rscons.clean
-    File.exists?('build_one/one.o').should be_false
-    File.exists?('build_two/two.o').should be_false
-    File.exists?('build_one').should be_false
-    File.exists?('build_two').should be_true
-    File.exists?('src/one/one.c').should be_true
+    expect(File.exists?('build_one/one.o')).to be_false
+    expect(File.exists?('build_two/two.o')).to be_false
+    expect(File.exists?('build_one')).to be_false
+    expect(File.exists?('build_two')).to be_true
+    expect(File.exists?('src/one/one.c')).to be_true
   end
 
   it 'allows Ruby classes as custom builders to be used to construct files' do
@@ -282,9 +282,9 @@ EOF
       env.Program('program', Dir['*.c'])
     end
 
-    lines.should == ["CC program.o", "LD program#{env["PROGSUFFIX"]}"]
-    File.exists?('inc.h').should be_true
-    `./program`.should == "The value is 5678\n"
+    expect(lines).to eq ["CC program.o", "LD program#{env["PROGSUFFIX"]}"]
+    expect(File.exists?('inc.h')).to be_true
+    expect(`./program`).to eq "The value is 5678\n"
   end
 
   it 'supports custom builders with multiple targets' do
@@ -309,15 +309,15 @@ EOF
       env.Program("program", Dir["*.c"] + ["inc.c"])
     end
 
-    lines.should == ["CHGen inc.c", "CC program.o", "CC inc.o", "LD program#{env["PROGSUFFIX"]}"]
-    File.exists?("inc.c").should be_true
-    File.exists?("inc.h").should be_true
-    `./program`.should == "The value is 42\n"
+    expect(lines).to eq ["CHGen inc.c", "CC program.o", "CC inc.o", "LD program#{env["PROGSUFFIX"]}"]
+    expect(File.exists?("inc.c")).to be_true
+    expect(File.exists?("inc.h")).to be_true
+    expect(`./program`).to eq "The value is 42\n"
 
     File.open("inc.c", "w") {|fh| fh.puts "int THE_VALUE = 33;"}
     env.process
-    lines.should == ["CHGen inc.c"]
-    `./program`.should == "The value is 42\n"
+    expect(lines).to eq ["CHGen inc.c"]
+    expect(`./program`).to eq "The value is 42\n"
   end
 
   it 'allows cloning Environment objects' do
@@ -336,7 +336,7 @@ EOF
       env.Program('program-release', Dir['src/*.c'])
     end
 
-    lines.should == [
+    expect(lines).to eq [
       %q{gcc -c -o debug/program.o -MMD -MF debug/program.mf '-DSTRING="Debug Version"' -O2 src/program.c},
       %Q{gcc -o program-debug#{debug["PROGSUFFIX"]} debug/program.o},
       %q{gcc -c -o release/program.o -MMD -MF release/program.mf '-DSTRING="Release Version"' -O2 src/program.c},
@@ -360,7 +360,7 @@ EOF
       env.Program('program2', Dir['src/*.c'])
     end
 
-    lines.should == [
+    expect(lines).to eq [
       %q{gcc -c -o build/program.o -MMD -MF build/program.mf -DSTRING="Hello" -O2 src/program.c},
       %Q{gcc -o program#{env1["PROGSUFFIX"]} build/program.o},
       %Q{gcc -o program2#{env2["PROGSUFFIX"]} build/program.o},
@@ -372,8 +372,8 @@ EOF
     Rscons::Environment.new do |env|
       env.Program('simple', Dir['*.cc'])
     end
-    File.exists?('simple.o').should be_true
-    `./simple`.should == "This is a simple C++ program\n"
+    expect(File.exists?('simple.o')).to be_true
+    expect(`./simple`).to eq "This is a simple C++ program\n"
   end
 
   it 'allows overriding construction variables for individual builder calls' do
@@ -382,13 +382,13 @@ EOF
       env.Object("one.o", "one.c", 'CPPFLAGS' => ['-DONE'])
       env.Program('two_sources', ['one.o', 'two.c'])
     end
-    lines.should == [
+    expect(lines).to eq [
       'gcc -c -o one.o -MMD -MF one.mf -DONE one.c',
       'gcc -c -o two.o -MMD -MF two.mf two.c',
       "gcc -o two_sources#{env["PROGSUFFIX"]} one.o two.o",
     ]
-    File.exists?("two_sources#{env["PROGSUFFIX"]}").should be_true
-    `./two_sources`.should == "This is a C program with two sources.\n"
+    expect(File.exists?("two_sources#{env["PROGSUFFIX"]}")).to be_true
+    expect(`./two_sources`).to eq "This is a C program with two sources.\n"
   end
 
   it 'builds a static library archive' do
@@ -397,15 +397,15 @@ EOF
       env.Program('library', ['lib.a', 'three.c'])
       env.Library("lib.a", ['one.c', 'two.c'], 'CPPFLAGS' => ['-Dmake_lib'])
     end
-    lines.should == [
+    expect(lines).to eq [
       'gcc -c -o one.o -MMD -MF one.mf -Dmake_lib one.c',
       'gcc -c -o two.o -MMD -MF two.mf -Dmake_lib two.c',
       'ar rcs lib.a one.o two.o',
       'gcc -c -o three.o -MMD -MF three.mf three.c',
       "gcc -o library#{env["PROGSUFFIX"]} lib.a three.o",
     ]
-    File.exists?("library#{env["PROGSUFFIX"]}").should be_true
-    `ar t lib.a`.should == "one.o\ntwo.o\n"
+    expect(File.exists?("library#{env["PROGSUFFIX"]}")).to be_true
+    expect(`ar t lib.a`).to eq "one.o\ntwo.o\n"
   end
 
   it 'supports build hooks to override construction variables' do
@@ -422,7 +422,7 @@ EOF
       end
       env.Program('build_hook.exe', Dir['src/**/*.c'])
     end
-    `./build_hook`.should == "Hello from two()\n"
+    expect(`./build_hook`).to eq "Hello from two()\n"
     lines.should =~ [
       'gcc -c -o build_one/one.o -MMD -MF build_one/one.mf -Isrc/one/ -Isrc/two/ -O1 src/one/one.c',
       'gcc -c -o build_two/two.o -MMD -MF build_two/two.mf -Isrc/one/ -Isrc/two/ -O2 src/two/two.c',
@@ -438,9 +438,9 @@ EOF
         fh.puts("foo")
       end
     end
-    lines.should == ["CC simple.o", "LD simple.exe"]
-    File.exists?('simple.o').should be_true
-    `./simple.exe`.should == "This is a simple C program\n"
+    expect(lines).to eq ["CC simple.o", "LD simple.exe"]
+    expect(File.exists?('simple.o')).to be_true
+    expect(`./simple.exe`).to eq "This is a simple C program\n"
     e2 = Rscons::Environment.new do |env|
       program = env.Program('simple.exe', Dir['*.c'])
       env.depends(program, "file.ld")
@@ -448,16 +448,16 @@ EOF
         fh.puts("bar")
       end
     end
-    lines.should == ["LD simple.exe"]
+    expect(lines).to eq ["LD simple.exe"]
     e3 = Rscons::Environment.new do |env|
       env.Program('simple.exe', Dir['*.c'])
       File.unlink("file.ld")
     end
-    lines.should == ["LD simple.exe"]
+    expect(lines).to eq ["LD simple.exe"]
     Rscons::Environment.new do |env|
       env.Program('simple.exe', Dir['*.c'])
     end
-    lines.should == []
+    expect(lines).to eq []
   end
 
   unless ENV["omit_gdc_tests"]
@@ -466,11 +466,11 @@ EOF
       Rscons::Environment.new(echo: :command) do |env|
         env.Program("hello-d.exe", Dir["*.d"])
       end
-      lines.should == [
+      expect(lines).to eq [
         "gdc -c -o main.o main.d",
         "gdc -o hello-d.exe main.o",
       ]
-      `./hello-d`.rstrip.should == "Hello from D!"
+      expect(`./hello-d`.rstrip).to eq "Hello from D!"
     end
   end
 
@@ -480,7 +480,7 @@ EOF
       env.Object("simple.o", "simple.c")
       env.Disassemble("simple.txt", "simple.o")
     end
-    File.exists?("simple.txt").should be_true
+    expect(File.exists?("simple.txt")).to be_true
     File.read("simple.txt").should =~ /Disassembly of section .text:/
   end
 
@@ -491,7 +491,7 @@ EOF
       env.Program("simple", "simplepp.c")
     end
     File.read("simplepp.c").should =~ /# \d+ "simple.c"/
-    `./simple`.should == "This is a simple C program\n"
+    expect(`./simple`).to eq "This is a simple C program\n"
   end
 
   it "supports preprocessing C++ sources" do
@@ -501,7 +501,7 @@ EOF
       env.Program("simple", "simplepp.cc")
     end
     File.read("simplepp.cc").should =~ /# \d+ "simple.cc"/
-    `./simple`.should == "This is a simple C++ program\n"
+    expect(`./simple`).to eq "This is a simple C++ program\n"
   end
 
   it "supports invoking builders with no sources and a build_root defined" do
@@ -539,8 +539,8 @@ EOF
       env.Program('program', "${src}")
     end
 
-    lines.should == ["CC program.o", "LD program#{env["PROGSUFFIX"]}"]
-    File.exists?('inc.h').should be_true
-    `./program`.should == "The value is 678\n"
+    expect(lines).to eq ["CC program.o", "LD program#{env["PROGSUFFIX"]}"]
+    expect(File.exists?('inc.h')).to be_true
+    expect(`./program`).to eq "The value is 678\n"
   end
 end
diff --git a/spec/rscons/cache_spec.rb b/spec/rscons/cache_spec.rb
index 1f72003..96a85a9 100644
--- a/spec/rscons/cache_spec.rb
+++ b/spec/rscons/cache_spec.rb
@@ -20,7 +20,7 @@ module Rscons
           $stderr.should_receive(:puts).with(/Warning:.*was.corrupt/)
           c = Cache.instance
           c.send(:initialize!)
-          c.instance_variable_get(:@cache).is_a?(Hash).should be_true
+          expect(c.instance_variable_get(:@cache).is_a?(Hash)).to be_true
         end
       end
     end
@@ -40,7 +40,7 @@ module Rscons
         fh.should_receive(:puts)
         File.should_receive(:open).and_yield(fh)
         build_from(cache).write
-        cache["version"].should == Rscons::VERSION
+        expect(cache["version"]).to eq Rscons::VERSION
       end
     end
 
@@ -52,12 +52,12 @@ module Rscons
 
       it "returns false when target file does not exist" do
         File.should_receive(:exists?).with("target").and_return(false)
-        build_from({}).up_to_date?("target", "command", [], empty_env).should be_false
+        expect(build_from({}).up_to_date?("target", "command", [], empty_env)).to be_false
       end
 
       it "returns false when target is not registered in the cache" do
         File.should_receive(:exists?).with("target").and_return(true)
-        build_from({}).up_to_date?("target", "command", [], empty_env).should be_false
+        expect(build_from({}).up_to_date?("target", "command", [], empty_env)).to be_false
       end
 
       it "returns false when the target's checksum does not match" do
@@ -65,7 +65,7 @@ module Rscons
         cache = build_from(_cache)
         File.should_receive(:exists?).with("target").and_return(true)
         cache.should_receive(:calculate_checksum).with("target").and_return("def")
-        cache.up_to_date?("target", "command", [], empty_env).should be_false
+        expect(cache.up_to_date?("target", "command", [], empty_env)).to be_false
       end
 
       it "returns false when the build command has changed" do
@@ -73,7 +73,7 @@ module Rscons
         cache = build_from(_cache)
         File.should_receive(:exists?).with("target").and_return(true)
         cache.should_receive(:calculate_checksum).with("target").and_return("abc")
-        cache.up_to_date?("target", "command", [], empty_env).should be_false
+        expect(cache.up_to_date?("target", "command", [], empty_env)).to be_false
       end
 
       it "returns false when there is a new dependency" do
@@ -83,7 +83,7 @@ module Rscons
         cache = build_from(_cache)
         File.should_receive(:exists?).with("target").and_return(true)
         cache.should_receive(:calculate_checksum).with("target").and_return("abc")
-        cache.up_to_date?("target", "command", ["dep.1", "dep.2"], empty_env).should be_false
+        expect(cache.up_to_date?("target", "command", ["dep.1", "dep.2"], empty_env)).to be_false
       end
 
       it "returns false when a dependency's checksum has changed" do
@@ -101,7 +101,7 @@ module Rscons
         cache.should_receive(:calculate_checksum).with("target").and_return("abc")
         cache.should_receive(:calculate_checksum).with("dep.1").and_return("dep.1.chk")
         cache.should_receive(:calculate_checksum).with("dep.2").and_return("dep.2.changed")
-        cache.up_to_date?("target", "command", ["dep.1", "dep.2"], empty_env).should be_false
+        expect(cache.up_to_date?("target", "command", ["dep.1", "dep.2"], empty_env)).to be_false
       end
 
       it "returns false with strict_deps=true when cache has an extra dependency" do
@@ -117,7 +117,7 @@ module Rscons
         cache = build_from(_cache)
         File.should_receive(:exists?).with("target").and_return(true)
         cache.should_receive(:calculate_checksum).with("target").and_return("abc")
-        cache.up_to_date?("target", "command", ["dep.1", "dep.2"], empty_env, strict_deps: true).should be_false
+        expect(cache.up_to_date?("target", "command", ["dep.1", "dep.2"], empty_env, strict_deps: true)).to be_false
       end
 
       it "returns false when there is a new user dependency" do
@@ -130,7 +130,7 @@ module Rscons
         env.should_receive(:get_user_deps).with("target").and_return(["file.ld"])
         File.should_receive(:exists?).with("target").and_return(true)
         cache.should_receive(:calculate_checksum).with("target").and_return("abc")
-        cache.up_to_date?("target", "command", ["dep.1"], env).should be_false
+        expect(cache.up_to_date?("target", "command", ["dep.1"], env)).to be_false
       end
 
       it "returns false when a user dependency checksum has changed" do
@@ -153,7 +153,7 @@ module Rscons
         cache.should_receive(:calculate_checksum).with("dep.2").and_return("dep.2.chk")
         cache.should_receive(:calculate_checksum).with("extra.dep").and_return("extra.dep.chk")
         cache.should_receive(:calculate_checksum).with("user.dep").and_return("INCORRECT")
-        cache.up_to_date?("target", "command", ["dep.1", "dep.2"], env).should be_false
+        expect(cache.up_to_date?("target", "command", ["dep.1", "dep.2"], env)).to be_false
       end
 
       it "returns true when no condition for false is met" do
@@ -172,7 +172,7 @@ module Rscons
         cache.should_receive(:calculate_checksum).with("dep.1").and_return("dep.1.chk")
         cache.should_receive(:calculate_checksum).with("dep.2").and_return("dep.2.chk")
         cache.should_receive(:calculate_checksum).with("extra.dep").and_return("extra.dep.chk")
-        cache.up_to_date?("target", "command", ["dep.1", "dep.2"], empty_env).should be_true
+        expect(cache.up_to_date?("target", "command", ["dep.1", "dep.2"], empty_env)).to be_true
       end
     end
 
@@ -189,13 +189,13 @@ module Rscons
         cache.register_build("the target", "the command", ["dep 1", "dep 2"], env)
         cached_target = cache.instance_variable_get(:@cache)["targets"]["the target"]
         cached_target.should_not be_nil
-        cached_target["command"].should == Digest::MD5.hexdigest("the command".inspect)
-        cached_target["checksum"].should == "the checksum"
-        cached_target["deps"].should == [
+        expect(cached_target["command"]).to eq Digest::MD5.hexdigest("the command".inspect)
+        expect(cached_target["checksum"]).to eq "the checksum"
+        expect(cached_target["deps"]).to eq [
           {"fname" => "dep 1", "checksum" => "dep 1 checksum"},
           {"fname" => "dep 2", "checksum" => "dep 2 checksum"},
         ]
-        cached_target["user_deps"].should == [
+        expect(cached_target["user_deps"]).to eq [
           {"fname" => "user.dep", "checksum" => "user.dep checksum"},
         ]
       end
@@ -204,7 +204,7 @@ module Rscons
     describe "#targets" do
       it "returns a list of targets that are cached" do
         cache = {"targets" => {"t1" => {}, "t2" => {}, "t3" => {}}}
-        build_from(cache).targets.should == ["t1", "t2", "t3"]
+        expect(build_from(cache).targets).to eq ["t1", "t2", "t3"]
       end
     end
 
@@ -223,7 +223,7 @@ module Rscons
         FileUtils.should_receive(:mkdir).with("one/two/four")
         cache.mkdir_p("one/two/three")
         cache.mkdir_p("one\\two\\four")
-        cache.directories.should == ["one/two", "one/two/three", "one/two/four"]
+        expect(cache.directories).to eq ["one/two", "one/two/three", "one/two/four"]
       end
 
       it "handles absolute paths" do
@@ -233,14 +233,14 @@ module Rscons
         File.should_receive(:exists?).with("/one/two").and_return(false)
         FileUtils.should_receive(:mkdir).with("/one/two")
         cache.mkdir_p("/one/two")
-        cache.directories.should == ["/one/two"]
+        expect(cache.directories).to eq ["/one/two"]
       end
     end
 
     describe "#directories" do
       it "returns a list of directories that are cached" do
         _cache = {"directories" => {"dir1" => true, "dir2" => true}}
-        build_from(_cache).directories.should == ["dir1", "dir2"]
+        expect(build_from(_cache).directories).to eq ["dir1", "dir2"]
       end
     end
 
@@ -249,13 +249,13 @@ module Rscons
         cache = build_from({})
         cache.instance_variable_set(:@lookup_checksums, {"f1" => "f1.chk"})
         cache.should_not_receive(:calculate_checksum)
-        cache.send(:lookup_checksum, "f1").should == "f1.chk"
+        expect(cache.send(:lookup_checksum, "f1")).to eq "f1.chk"
       end
 
       it "calls calculate_checksum when the checksum is not cached" do
         cache = build_from({})
         cache.should_receive(:calculate_checksum).with("f1").and_return("ck")
-        cache.send(:lookup_checksum, "f1").should == "ck"
+        expect(cache.send(:lookup_checksum, "f1")).to eq "ck"
       end
     end
 
@@ -264,7 +264,7 @@ module Rscons
         contents = "contents"
         File.should_receive(:read).with("fname", mode: "rb").and_return(contents)
         Digest::MD5.should_receive(:hexdigest).with(contents).and_return("the_checksum")
-        build_from({}).send(:calculate_checksum, "fname").should == "the_checksum"
+        expect(build_from({}).send(:calculate_checksum, "fname")).to eq "the_checksum"
       end
     end
   end
diff --git a/spec/rscons/environment_spec.rb b/spec/rscons/environment_spec.rb
index d925766..8802078 100644
--- a/spec/rscons/environment_spec.rb
+++ b/spec/rscons/environment_spec.rb
@@ -4,7 +4,7 @@ module Rscons
       it "adds the default builders when they are not excluded" do
         env = Environment.new
         env.builders.size.should be > 0
-        env.builders.map {|name, builder| builder.is_a?(Builder)}.all?.should be_true
+        expect(env.builders.map {|name, builder| builder.is_a?(Builder)}.all?).to be_true
         env.builders.find {|name, builder| name == "Object"}.should_not be_nil
         env.builders.find {|name, builder| name == "Program"}.should_not be_nil
         env.builders.find {|name, builder| name == "Library"}.should_not be_nil
@@ -12,7 +12,7 @@ module Rscons
 
       it "excludes the default builders with exclude_builders: :all" do
         env = Environment.new(exclude_builders: true)
-        env.builders.size.should == 0
+        expect(env.builders.size).to eq 0
       end
 
       context "when a block is given" do
@@ -30,8 +30,8 @@ module Rscons
         env["CPPPATH"] << "path1"
         env2 = env.clone
         env2["CPPPATH"] << "path2"
-        env["CPPPATH"].should == ["path1"]
-        env2["CPPPATH"].should == ["path1", "path2"]
+        expect(env["CPPPATH"]).to eq ["path1"]
+        expect(env2["CPPPATH"]).to eq ["path1", "path2"]
       end
 
       it "supports nil, false, true, String, Symbol, Array, Hash, and Integer variables" do
@@ -68,9 +68,9 @@ module Rscons
     describe "#add_builder" do
       it "adds the builder to the list of builders" do
         env = Environment.new(exclude_builders: true)
-        env.builders.keys.should == []
+        expect(env.builders.keys).to eq []
         env.add_builder(Rscons::Builders::Object.new)
-        env.builders.keys.should == ["Object"]
+        expect(env.builders.keys).to eq ["Object"]
       end
     end
 
@@ -78,20 +78,20 @@ module Rscons
       context "with no build directories" do
         it "returns the name of the source file with suffix changed" do
           env = Environment.new
-          env.get_build_fname("src/dir/file.c", ".o").should == "src/dir/file.o"
-          env.get_build_fname("src\\dir\\other.d", ".a").should == "src/dir/other.a"
-          env.get_build_fname("source.cc", ".o").should == "source.o"
+          expect(env.get_build_fname("src/dir/file.c", ".o")).to eq "src/dir/file.o"
+          expect(env.get_build_fname("src\\dir\\other.d", ".a")).to eq "src/dir/other.a"
+          expect(env.get_build_fname("source.cc", ".o")).to eq "source.o"
         end
 
         context "with a build_root" do
           it "uses the build_root unless the path is absolute" do
             env = Environment.new
             env.build_root = "build/proj"
-            env.get_build_fname("src/dir/file.c", ".o").should == "build/proj/src/dir/file.o"
-            env.get_build_fname("/some/lib.c", ".a").should == "/some/lib.a"
-            env.get_build_fname("C:\\abspath\\mod.cc", ".o").should == "C:/abspath/mod.o"
-            env.get_build_fname("build\\proj\\generated.c", ".o").should == "build/proj/generated.o"
-            env.get_build_fname("build/proj.XX", ".yy").should == "build/proj/build/proj.yy"
+            expect(env.get_build_fname("src/dir/file.c", ".o")).to eq "build/proj/src/dir/file.o"
+            expect(env.get_build_fname("/some/lib.c", ".a")).to eq "/some/lib.a"
+            expect(env.get_build_fname("C:\\abspath\\mod.cc", ".o")).to eq "C:/abspath/mod.o"
+            expect(env.get_build_fname("build\\proj\\generated.c", ".o")).to eq "build/proj/generated.o"
+            expect(env.get_build_fname("build/proj.XX", ".yy")).to eq "build/proj/build/proj.yy"
           end
         end
       end
@@ -101,10 +101,10 @@ module Rscons
           env = Environment.new
           env.build_dir("src", "bld")
           env.build_dir(%r{^libs/([^/]+)}, 'build/libs/\1')
-          env.get_build_fname("src/input.cc", ".o").should == "bld/input.o"
-          env.get_build_fname("libs/lib1/some/file.c", ".o").should == "build/libs/lib1/some/file.o"
-          env.get_build_fname("libs/otherlib/otherlib.cc", ".o").should == "build/libs/otherlib/otherlib.o"
-          env.get_build_fname("other_directory/o.d", ".a").should == "other_directory/o.a"
+          expect(env.get_build_fname("src/input.cc", ".o")).to eq "bld/input.o"
+          expect(env.get_build_fname("libs/lib1/some/file.c", ".o")).to eq "build/libs/lib1/some/file.o"
+          expect(env.get_build_fname("libs/otherlib/otherlib.cc", ".o")).to eq "build/libs/otherlib/otherlib.o"
+          expect(env.get_build_fname("other_directory/o.d", ".a")).to eq "other_directory/o.a"
         end
 
         context "with a build_root" do
@@ -114,11 +114,11 @@ module Rscons
             env.build_dir(%r{^libs/([^/]+)}, 'build/libs/\1')
             env.build_root = "bldit"
 
-            env.get_build_fname("src/input.cc", ".o").should == "bld/input.o"
-            env.get_build_fname("libs/lib1/some/file.c", ".o").should == "build/libs/lib1/some/file.o"
-            env.get_build_fname("libs/otherlib/otherlib.cc", ".o").should == "build/libs/otherlib/otherlib.o"
-            env.get_build_fname("other_directory/o.d", ".a").should == "bldit/other_directory/o.a"
-            env.get_build_fname("bldit/some/mod.d", ".a").should == "bldit/some/mod.a"
+            expect(env.get_build_fname("src/input.cc", ".o")).to eq "bld/input.o"
+            expect(env.get_build_fname("libs/lib1/some/file.c", ".o")).to eq "build/libs/lib1/some/file.o"
+            expect(env.get_build_fname("libs/otherlib/otherlib.cc", ".o")).to eq "build/libs/otherlib/otherlib.o"
+            expect(env.get_build_fname("other_directory/o.d", ".a")).to eq "bldit/other_directory/o.a"
+            expect(env.get_build_fname("bldit/some/mod.d", ".a")).to eq "bldit/some/mod.a"
           end
         end
       end
@@ -128,7 +128,7 @@ module Rscons
       it "allows reading construction variables" do
         env = Environment.new
         env["CFLAGS"] = ["-g", "-Wall"]
-        env["CFLAGS"].should == ["-g", "-Wall"]
+        expect(env["CFLAGS"]).to eq ["-g", "-Wall"]
       end
     end
 
@@ -138,9 +138,9 @@ module Rscons
         env["CFLAGS"] = ["-g", "-Wall"]
         env["CFLAGS"] -= ["-g"]
         env["CFLAGS"] += ["-O3"]
-        env["CFLAGS"].should == ["-Wall", "-O3"]
+        expect(env["CFLAGS"]).to eq ["-Wall", "-O3"]
         env["other_var"] = "val33"
-        env["other_var"].should == "val33"
+        expect(env["other_var"]).to eq "val33"
       end
     end
 
@@ -150,8 +150,8 @@ module Rscons
         env["CFLAGS"] = ["-g"]
         env["CPPPATH"] = ["inc"]
         env.append("CFLAGS" => ["-Wall"], "CPPPATH" => ["include"])
-        env["CFLAGS"].should == ["-Wall"]
-        env["CPPPATH"].should == ["include"]
+        expect(env["CFLAGS"]).to eq ["-Wall"]
+        expect(env["CPPPATH"]).to eq ["include"]
       end
     end
 
@@ -234,7 +234,7 @@ module Rscons
         env["specialflag"] = "-z"
         template = ["cmd", "-I${path}", "${flags}", "${_source}", "${_dest}"]
         cmd = env.build_command(template, "_source" => "infile", "_dest" => "outfile")
-        cmd.should == ["cmd", "-Idir1", "-Idir2", "-x", "-y", "-z", "infile", "outfile"]
+        expect(cmd).to eq ["cmd", "-Idir1", "-Idir2", "-x", "-y", "-z", "infile", "outfile"]
       end
     end
 
@@ -245,11 +245,11 @@ module Rscons
         env["flags"] = ["-x", "-y", "${specialflag}"]
         env["specialflag"] = "-z"
         env["foo"] = {}
-        env.expand_varref(["-p${path}", "${flags}"]).should == ["-pdir1", "-pdir2", "-x", "-y", "-z"]
-        env.expand_varref("foo").should == "foo"
+        expect(env.expand_varref(["-p${path}", "${flags}"])).to eq ["-pdir1", "-pdir2", "-x", "-y", "-z"]
+        expect(env.expand_varref("foo")).to eq "foo"
         expect {env.expand_varref("${foo}")}.to raise_error /expand.a.variable.reference/
-        env.expand_varref("${specialflag}").should == "-z"
-        env.expand_varref("${path}").should == ["dir1", "dir2"]
+        expect(env.expand_varref("${specialflag}")).to eq "-z"
+        expect(env.expand_varref("${path}")).to eq ["dir1", "dir2"]
       end
     end
 
@@ -294,14 +294,14 @@ module Rscons
 
       it "records the target when the target method is a known builder" do
         env = Environment.new
-        env.instance_variable_get(:@targets).should == {}
+        expect(env.instance_variable_get(:@targets)).to eq({})
         env.Object("target.o", ["src1.c", "src2.c"], var: "val")
         target = env.instance_variable_get(:@targets)["target.o"]
         target.should_not be_nil
-        target[:builder].is_a?(Builder).should be_true
-        target[:sources].should == ["src1.c", "src2.c"]
-        target[:vars].should == {var: "val"}
-        target[:args].should == []
+        expect(target[:builder].is_a?(Builder)).to be_true
+        expect(target[:sources]).to eq ["src1.c", "src2.c"]
+        expect(target[:vars]).to eq({var: "val"})
+        expect(target[:args]).to eq []
       end
 
       it "raises an error when vars is not a Hash" do
@@ -314,13 +314,13 @@ module Rscons
       it "records the given dependencies in @user_deps" do
         env = Environment.new
         env.depends("foo", "bar", "baz")
-        env.instance_variable_get(:@user_deps).should == {"foo" => ["bar", "baz"]}
+        expect(env.instance_variable_get(:@user_deps)).to eq({"foo" => ["bar", "baz"]})
       end
       it "records user dependencies only once" do
         env = Environment.new
         env.instance_variable_set(:@user_deps, {"foo" => ["bar"]})
         env.depends("foo", "bar", "baz")
-        env.instance_variable_get(:@user_deps).should == {"foo" => ["bar", "baz"]}
+        expect(env.instance_variable_get(:@user_deps)).to eq({"foo" => ["bar", "baz"]})
       end
     end
 
@@ -337,7 +337,7 @@ module Rscons
         env.add_builder(ABuilder.new)
         env.builders["Object"].should_receive(:run).with("mod.o", ["mod.c"], cache, env, anything).and_return("mod.o")
         env.builders["ABuilder"].should_receive(:run).with("mod2.ab_out", ["mod2.ab_in"], cache, env, anything).and_return("mod2.ab_out")
-        env.build_sources(["precompiled.o", "mod.c", "mod2.ab_in"], [".o", ".ab_out"], cache, {}).should == ["precompiled.o", "mod.o", "mod2.ab_out"]
+        expect(env.build_sources(["precompiled.o", "mod.c", "mod2.ab_in"], [".o", ".ab_out"], cache, {})).to eq ["precompiled.o", "mod.o", "mod2.ab_out"]
       end
     end
 
@@ -350,11 +350,11 @@ module Rscons
           end
         end
         env.builders["Object"].stub(:run) do |target, sources, cache, env, vars|
-          vars["CFLAGS"].should == []
+          expect(vars["CFLAGS"]).to eq []
         end
         env.run_builder(env.builders["Object"], "build/normal/module.o", ["src/normal/module.c"], "cache", {})
         env.builders["Object"].stub(:run) do |target, sources, cache, env, vars|
-          vars["CFLAGS"].should == ["-O3", "-DSPECIAL"]
+          expect(vars["CFLAGS"]).to eq ["-O3", "-DSPECIAL"]
         end
         env.run_builder(env.builders["Object"], "build/special/module.o", ["src/special/module.c"], "cache", {})
       end
@@ -438,7 +438,7 @@ module Rscons
         File.should_receive(:read).with('makefile').and_return(<<EOS)
 module.o: source.cc
 EOS
-        Environment.parse_makefile_deps('makefile', 'module.o').should == ['source.cc']
+        expect(Environment.parse_makefile_deps('makefile', 'module.o')).to eq ['source.cc']
       end
 
       it 'handles dependencies split across many lines' do
@@ -447,7 +447,7 @@ module.o: module.c \\
   module.h \\
   other.h
 EOS
-        Environment.parse_makefile_deps('makefile', 'module.o').should == [
+        expect(Environment.parse_makefile_deps('makefile', 'module.o')).to eq [
           'module.c', 'module.h', 'other.h']
       end
     end
diff --git a/spec/rscons/varset_spec.rb b/spec/rscons/varset_spec.rb
index 4387838..8c12961 100644
--- a/spec/rscons/varset_spec.rb
+++ b/spec/rscons/varset_spec.rb
@@ -3,20 +3,20 @@ module Rscons
     describe '#initialize' do
       it "initializes variables from a Hash" do
         v = VarSet.new({"one" => 1, "two" => :two})
-        v["one"].should == 1
-        v["two"].should == :two
+        expect(v["one"]).to eq(1)
+        expect(v["two"]).to eq(:two)
       end
       it "initializes variables from another VarSet" do
         v = VarSet.new({"one" => 1})
         v2 = VarSet.new(v)
-        v2["one"].should == 1
+        expect(v2["one"]).to eq 1
       end
       it "makes a deep copy of the given VarSet" do
         v = VarSet.new({"array" => [1, 2, 3]})
         v2 = VarSet.new(v)
         v["array"] << 4
-        v["array"].should == [1, 2, 3, 4]
-        v2["array"].should == [1, 2, 3]
+        expect(v["array"]).to eq([1, 2, 3, 4])
+        expect(v2["array"]).to eq([1, 2, 3])
       end
     end
 
@@ -24,11 +24,11 @@ module Rscons
       it "allows accessing a variable with its verbatim value if type is not specified" do
         v = VarSet.new({"fuz" => "a string", "foo" => 42, "bar" => :baz,
                         "qax" => [3, 6], "qux" => {a: :b}})
-        v["fuz"].should == "a string"
-        v["foo"].should == 42
-        v["bar"].should == :baz
-        v["qax"].should == [3, 6]
-        v["qux"].should == {a: :b}
+        expect(v["fuz"]).to eq("a string")
+        expect(v["foo"]).to eq(42)
+        expect(v["bar"]).to eq(:baz)
+        expect(v["qax"]).to eq([3, 6])
+        expect(v["qux"]).to eq({a: :b})
       end
     end
 
@@ -36,8 +36,8 @@ module Rscons
       it "allows assigning to variables" do
         v = VarSet.new("CFLAGS" => ["-Wall", "-O3"])
         v["CPPPATH"] = ["one", "two"]
-        v["CFLAGS"].should == ["-Wall", "-O3"]
-        v["CPPPATH"].should == ["one", "two"]
+        expect(v["CFLAGS"]).to eq(["-Wall", "-O3"])
+        expect(v["CPPPATH"]).to eq(["one", "two"])
       end
     end
 
@@ -128,29 +128,29 @@ module Rscons
                      "cmd" => ["${CC}", "-c", "${CFLAGS}", "-I${CPPPATH}"],
                      "hash" => {})
       it "expands to the string itself if the string is not a variable reference" do
-        v.expand_varref("CC").should == "CC"
-        v.expand_varref("CPPPATH").should == "CPPPATH"
-        v.expand_varref("str").should == "str"
+        expect(v.expand_varref("CC")).to eq("CC")
+        expect(v.expand_varref("CPPPATH")).to eq("CPPPATH")
+        expect(v.expand_varref("str")).to eq("str")
       end
       it "expands a single variable reference beginning with a '$'" do
-        v.expand_varref("${CC}").should == "gcc"
-        v.expand_varref("${CPPPATH}").should == ["dir1", "dir2"]
+        expect(v.expand_varref("${CC}")).to eq("gcc")
+        expect(v.expand_varref("${CPPPATH}")).to eq(["dir1", "dir2"])
       end
       it "expands a single variable reference in ${arr} notation" do
-        v.expand_varref("prefix${CFLAGS}suffix").should == ["prefix-Wallsuffix", "prefix-O2suffix"]
-        v.expand_varref(v["cmd"]).should == ["gcc", "-c", "-Wall", "-O2", "-Idir1", "-Idir2"]
+        expect(v.expand_varref("prefix${CFLAGS}suffix")).to eq(["prefix-Wallsuffix", "prefix-O2suffix"])
+        expect(v.expand_varref(v["cmd"])).to eq(["gcc", "-c", "-Wall", "-O2", "-Idir1", "-Idir2"])
       end
       it "expands a variable reference recursively" do
-        v.expand_varref("${compiler}").should == "gcc"
-        v.expand_varref("${cmd}").should == ["gcc", "-c", "-Wall", "-O2", "-Idir1", "-Idir2"]
+        expect(v.expand_varref("${compiler}")).to eq("gcc")
+        expect(v.expand_varref("${cmd}")).to eq(["gcc", "-c", "-Wall", "-O2", "-Idir1", "-Idir2"])
       end
       it "resolves multiple variable references in one element by enumerating all combinations" do
-        v.expand_varref("cflag: ${CFLAGS}, cpppath: ${CPPPATH}, compiler: ${compiler}").should == [
+        expect(v.expand_varref("cflag: ${CFLAGS}, cpppath: ${CPPPATH}, compiler: ${compiler}")).to eq([
           "cflag: -Wall, cpppath: dir1, compiler: gcc",
           "cflag: -O2, cpppath: dir1, compiler: gcc",
           "cflag: -Wall, cpppath: dir2, compiler: gcc",
           "cflag: -O2, cpppath: dir2, compiler: gcc",
-        ]
+        ])
       end
       it "returns an empty string when a variable reference refers to a non-existent variable" do
         expect(v.expand_varref("${not_here}")).to eq("")