diff --git a/build_tests/simple/progsuffix2.rb b/build_tests/simple/progsuffix2.rb
new file mode 100644
index 0000000..8f7ce00
--- /dev/null
+++ b/build_tests/simple/progsuffix2.rb
@@ -0,0 +1,4 @@
+Rscons::Environment.new do |env|
+  env["MYSUFFIX"] = ".out"
+  env.Program("simple${MYSUFFIX}", Dir["*.c"])
+end
diff --git a/build_tests/simple/progsuffix3.rb b/build_tests/simple/progsuffix3.rb
new file mode 100644
index 0000000..9552a3f
--- /dev/null
+++ b/build_tests/simple/progsuffix3.rb
@@ -0,0 +1,3 @@
+Rscons::Environment.new do |env|
+  env.Program("simple", Dir["*.c"], "PROGSUFFIX" => ".xyz")
+end
diff --git a/lib/rscons/builder.rb b/lib/rscons/builder.rb
index fb8a8ad..3a3e62b 100644
--- a/lib/rscons/builder.rb
+++ b/lib/rscons/builder.rb
@@ -36,6 +36,8 @@ module Rscons
     #   The user-supplied target name.
     # @option options [Array<String>] :sources
     #   The user-supplied source file name(s).
+    # @option options [Hash,VarSet] :vars
+    #   Extra construction variables.
     #
     # @return [BuildTarget]
     def create_build_target(options)
diff --git a/lib/rscons/builders/program.rb b/lib/rscons/builders/program.rb
index d558858..45f9f8f 100644
--- a/lib/rscons/builders/program.rb
+++ b/lib/rscons/builders/program.rb
@@ -39,9 +39,10 @@ module Rscons
       #
       # @return [BuildTarget]
       def create_build_target(options)
+        env, target, vars = options.values_at(:env, :target, :vars)
         my_options = options.dup
-        unless my_options[:target] =~ /\./
-          my_options[:target] += options[:env].expand_varref("${PROGSUFFIX}")
+        unless env.expand_varref(target, vars) =~ /\./
+          my_options[:target] += env.expand_varref("${PROGSUFFIX}", vars)
         end
         super(my_options)
       end
diff --git a/lib/rscons/environment.rb b/lib/rscons/environment.rb
index 805ed86..f120e02 100644
--- a/lib/rscons/environment.rb
+++ b/lib/rscons/environment.rb
@@ -409,7 +409,7 @@ module Rscons
         end
         sources = Array(sources)
         builder = @builders[method.to_s]
-        build_target = builder.create_build_target(env: self, target: target, sources: sources)
+        build_target = builder.create_build_target(env: self, target: target, sources: sources, vars: vars)
         add_target(build_target.to_s, builder, sources, vars || {}, rest)
         build_target
       else
diff --git a/spec/build_tests_spec.rb b/spec/build_tests_spec.rb
index 4ff375a..3b61882 100644
--- a/spec/build_tests_spec.rb
+++ b/spec/build_tests_spec.rb
@@ -632,7 +632,7 @@ EOF
     ]
   end
 
-  it "allows overriding progsuffix" do
+  it "allows overriding PROGSUFFIX" do
     test_dir("simple")
     result = run_test(rsconsfile: "progsuffix.rb")
     expect(result.stderr).to eq ""
@@ -642,6 +642,26 @@ EOF
     ]
   end
 
+  it "does not use PROGSUFFIX when the Program target name expands to a value already containing an extension" do
+    test_dir("simple")
+    result = run_test(rsconsfile: "progsuffix2.rb")
+    expect(result.stderr).to eq ""
+    expect(lines(result.stdout)).to eq [
+      "CC simple.o",
+      "LD simple.out",
+    ]
+  end
+
+  it "allows overriding PROGSUFFIX from extra vars passed in to the builder" do
+    test_dir("simple")
+    result = run_test(rsconsfile: "progsuffix3.rb")
+    expect(result.stderr).to eq ""
+    expect(lines(result.stdout)).to eq [
+      "CC simple.o",
+      "LD simple.xyz",
+    ]
+  end
+
   context "backward compatibility" do
     it "allows a builder to call Environment#run_builder in a non-threaded manner" do
       test_dir("simple")