diff --git a/build_tests/configure/custom_config_check.rb b/build_tests/configure/custom_config_check.rb
new file mode 100644
index 0000000..769e510
--- /dev/null
+++ b/build_tests/configure/custom_config_check.rb
@@ -0,0 +1,26 @@
+configure do
+  custom_check("Checking 'grep' version") do |op|
+    stdout, stderr, status = op.log_and_test_command(%w[grep --version])
+    should_fail = true
+    if status != 0
+      fail_message = "error executing grep"
+    elsif stdout =~ /^grep \(GNU grep\) 1\./
+      fail_message = "too old!"
+      status = 1
+    elsif stdout =~ /^grep \(GNU grep\) 2\./
+      fail_message = "we'll work with it but you should upgrade"
+      status = 1
+      should_fail = false
+      op.store_merge("CPPDEFINES" => "GREP_WORKAROUND")
+    else
+      op.store_append("CPPDEFINES" => "GREP_FULL")
+    end
+    op.complete(status, success_message: "good!", fail_message: fail_message, fail: should_fail)
+  end
+end
+
+build do
+  Environment.new do |env|
+    puts env["CPPDEFINES"]
+  end
+end
diff --git a/lib/rscons/configure_op.rb b/lib/rscons/configure_op.rb
index ed63dd5..5a607ab 100644
--- a/lib/rscons/configure_op.rb
+++ b/lib/rscons/configure_op.rb
@@ -69,7 +69,7 @@ module Rscons
       cc = ccc.find do |cc|
         test_c_compiler(cc)
       end
-      common_config_checks(cc ? 0 : 1, success_message: cc)
+      complete(cc ? 0 : 1, success_message: cc)
     end
 
     # Check for a working C++ compiler.
@@ -87,7 +87,7 @@ module Rscons
       cc = ccc.find do |cc|
         test_cxx_compiler(cc)
       end
-      common_config_checks(cc ? 0 : 1, success_message: cc)
+      complete(cc ? 0 : 1, success_message: cc)
     end
 
     # Check for a working D compiler.
@@ -105,7 +105,7 @@ module Rscons
       dc = cdc.find do |dc|
         test_d_compiler(dc)
       end
-      common_config_checks(dc ? 0 : 1, success_message: dc)
+      complete(dc ? 0 : 1, success_message: dc)
     end
 
     # Check for a package or configure program output.
@@ -122,7 +122,7 @@ module Rscons
       if status == 0
         store_parse(stdout, options)
       end
-      common_config_checks(status, options)
+      complete(status, options)
     end
 
     # Check for a C header.
@@ -158,7 +158,7 @@ module Rscons
           break
         end
       end
-      common_config_checks(status, options)
+      complete(status, options)
     end
 
     # Check for a C++ header.
@@ -194,7 +194,7 @@ module Rscons
           break
         end
       end
-      common_config_checks(status, options)
+      complete(status, options)
     end
 
     # Check for a D import.
@@ -230,7 +230,7 @@ module Rscons
           break
         end
       end
-      common_config_checks(status, options)
+      complete(status, options)
     end
 
     # Check for a library.
@@ -268,14 +268,113 @@ module Rscons
       if status == 0
         store_append({"LIBS" => [lib]}, options)
       end
-      common_config_checks(status, options)
+      complete(status, options)
     end
 
     # Check for a executable program.
     def check_program(program, options = {})
       Ansi.write($stdout, "Checking for program '", :cyan, program, :reset, "'... ")
       path = Util.find_executable(program)
-      common_config_checks(path ? 0 : 1, options.merge(success_message: path))
+      complete(path ? 0 : 1, options.merge(success_message: path))
+    end
+
+    # Execute a test command and log the result.
+    #
+    # @return [String, String, Process::Status]
+    #   stdout, stderr, status
+    def log_and_test_command(command)
+      begin
+        @log_fh.puts("Command: #{command.join(" ")}")
+        stdout, stderr, status = Open3.capture3(*command)
+        @log_fh.puts("Exit status: #{status.to_i}")
+        @log_fh.write(stdout)
+        @log_fh.write(stderr)
+        [stdout, stderr, status]
+      rescue Errno::ENOENT
+        ["", "", 127]
+      end
+    end
+
+    # Store construction variables for merging into the Cache.
+    #
+    # @param vars [Hash]
+    #   Hash containing the variables to merge.
+    # @param options [Hash]
+    #   Options.
+    def store_merge(vars, options = {})
+      store_vars = store_common(options)
+      store_vars["merge"] ||= {}
+      vars.each_pair do |key, value|
+        store_vars["merge"][key] = value
+      end
+    end
+
+    # Store construction variables for appending into the Cache.
+    #
+    # @param vars [Hash]
+    #   Hash containing the variables to append.
+    # @param options [Hash]
+    #   Options.
+    def store_append(vars, options = {})
+      store_vars = store_common(options)
+      store_vars["append"] ||= {}
+      vars.each_pair do |key, value|
+        if store_vars["append"][key].is_a?(Array) and value.is_a?(Array)
+          store_vars["append"][key] += value
+        else
+          store_vars["append"][key] = value
+        end
+      end
+    end
+
+    # Store flags to be parsed into the Cache.
+    #
+    # @param flags [String]
+    #   String containing the flags to parse.
+    # @param options [Hash]
+    #   Options.
+    def store_parse(flags, options = {})
+      store_vars = store_common(options)
+      store_vars["parse"] ||= []
+      store_vars["parse"] << flags
+    end
+
+    # Perform processing common to several configure checks.
+    #
+    # @param status [Process::Status, Integer]
+    #   Process exit code. 0 for success, non-zero for error.
+    # @param options [Hash]
+    #   Common check options.
+    # @option options [Boolean] :fail
+    #   Whether to fail configuration if the requested item is not found.
+    #   This defaults to true if the :set_define option is not specified,
+    #   otherwise defaults to false if :set_define option is specified.
+    # @option options [String] :set_define
+    #   A define to set (in CPPDEFINES) if the requested item is found.
+    # @option options [String] :success_message
+    #   Message to print on success (default "found").
+    def complete(status, options)
+      success_message = options[:success_message] || "found"
+      fail_message = options[:fail_message] || "not found"
+      if status == 0
+        Ansi.write($stdout, :green, "#{success_message}\n")
+        if options[:set_define]
+          store_append("CPPDEFINES" => [options[:set_define]])
+        end
+      else
+        should_fail =
+          if options.has_key?(:fail)
+            options[:fail]
+          else
+            !options[:set_define]
+          end
+        if should_fail
+          Ansi.write($stdout, :red, "#{fail_message}\n")
+          raise ConfigureFailure.new
+        else
+          Ansi.write($stdout, :yellow, "#{fail_message}\n")
+        end
+      end
     end
 
     private
@@ -381,64 +480,6 @@ module Rscons
       end
     end
 
-    # Execute a test command and log the result.
-    def log_and_test_command(command)
-      begin
-        @log_fh.puts("Command: #{command.join(" ")}")
-        stdout, stderr, status = Open3.capture3(*command)
-        @log_fh.puts("Exit status: #{status.to_i}")
-        @log_fh.write(stdout)
-        @log_fh.write(stderr)
-        [stdout, stderr, status]
-      rescue Errno::ENOENT
-        ["", "", 127]
-      end
-    end
-
-    # Store construction variables for merging into the Cache.
-    #
-    # @param vars [Hash]
-    #   Hash containing the variables to merge.
-    # @param options [Hash]
-    #   Options.
-    def store_merge(vars, options = {})
-      store_vars = store_common(options)
-      store_vars["merge"] ||= {}
-      vars.each_pair do |key, value|
-        store_vars["merge"][key] = value
-      end
-    end
-
-    # Store construction variables for appending into the Cache.
-    #
-    # @param vars [Hash]
-    #   Hash containing the variables to append.
-    # @param options [Hash]
-    #   Options.
-    def store_append(vars, options = {})
-      store_vars = store_common(options)
-      store_vars["append"] ||= {}
-      vars.each_pair do |key, value|
-        if store_vars["append"][key].is_a?(Array) and value.is_a?(Array)
-          store_vars["append"][key] += value
-        else
-          store_vars["append"][key] = value
-        end
-      end
-    end
-
-    # Store flags to be parsed into the Cache.
-    #
-    # @param flags [String]
-    #   String containing the flags to parse.
-    # @param options [Hash]
-    #   Options.
-    def store_parse(flags, options = {})
-      store_vars = store_common(options)
-      store_vars["parse"] ||= []
-      store_vars["parse"] << flags
-    end
-
     # Common functionality for all store methods.
     #
     # @param options [Hash]
@@ -462,42 +503,5 @@ module Rscons
       end
     end
 
-    # Perform processing common to several configure checks.
-    #
-    # @param status [Process::Status, Integer]
-    #   Process exit code.
-    # @param options [Hash]
-    #   Common check options.
-    # @option options [Boolean] :fail
-    #   Whether to fail configuration if the requested item is not found.
-    #   This defaults to true if the :set_define option is not specified,
-    #   otherwise defaults to false if :set_define option is specified.
-    # @option options [String] :set_define
-    #   A define to set (in CPPDEFINES) if the requested item is found.
-    # @option options [String] :success_message
-    #   Message to print on success (default "found").
-    def common_config_checks(status, options)
-      success_message = options[:success_message] || "found"
-      if status == 0
-        Ansi.write($stdout, :green, "#{success_message}\n")
-        if options[:set_define]
-          store_append("CPPDEFINES" => [options[:set_define]])
-        end
-      else
-        should_fail =
-          if options.has_key?(:fail)
-            options[:fail]
-          else
-            !options[:set_define]
-          end
-        if should_fail
-          Ansi.write($stdout, :red, "not found\n")
-          raise ConfigureFailure.new
-        else
-          Ansi.write($stdout, :yellow, "not found\n")
-        end
-      end
-    end
-
   end
 end
diff --git a/lib/rscons/script.rb b/lib/rscons/script.rb
index eba8702..13cb44d 100644
--- a/lib/rscons/script.rb
+++ b/lib/rscons/script.rb
@@ -81,6 +81,19 @@ module Rscons
           @configure_op.__send__(method_name, *args)
         end
       end
+
+      # Perform a custom configuration check.
+      #
+      # @param message [String]
+      #   Custom configuration check message (e.g. "Checking for foo").
+      #   rscons will add "... " to the end of the message.
+      # @yieldparam configure_op [ConfigureOp]
+      #   {ConfigureOp} object.
+      # @return [void]
+      def custom_check(message, &block)
+        $stdout.write(message + "... ")
+        block[@configure_op]
+      end
     end
 
     # @return [String, nil]
diff --git a/spec/build_tests_spec.rb b/spec/build_tests_spec.rb
index dacf906..d628f27 100644
--- a/spec/build_tests_spec.rb
+++ b/spec/build_tests_spec.rb
@@ -2086,6 +2086,66 @@ EOF
       end
     end
 
+    context "custom_check" do
+      context "when running a test command" do
+        context "when executing the command fails" do
+          context "when failures are fatal" do
+            it "fails configuration with the correct error message" do
+              test_dir "configure"
+              create_exe "grep", "exit 4"
+              result = run_rscons(rsconscript: "custom_config_check.rb", op: "configure")
+              expect(result.stderr).to eq ""
+              expect(result.stdout).to match /Checking 'grep' version\.\.\. error executing grep/
+              expect(result.status).to_not eq 0
+            end
+          end
+
+          context "when the custom logic indicates a failure" do
+            it "fails configuration with the correct error message" do
+              test_dir "configure"
+              create_exe "grep", "echo 'grep (GNU grep) 1.1'"
+              result = run_rscons(rsconscript: "custom_config_check.rb", op: "configure")
+              expect(result.stderr).to eq ""
+              expect(result.stdout).to match /Checking 'grep' version\.\.\. too old!/
+              expect(result.status).to_not eq 0
+            end
+          end
+        end
+
+        context "when failures are not fatal" do
+          context "when the custom logic indicates a failure" do
+            it "displays the correct message and does not fail configuration" do
+              test_dir "configure"
+              create_exe "grep", "echo 'grep (GNU grep) 2.1'"
+              result = run_rscons(rsconscript: "custom_config_check.rb", op: "configure")
+              expect(result.stderr).to eq ""
+              expect(result.stdout).to match /Checking 'grep' version\.\.\. we'll work with it but you should upgrade/
+              expect(result.status).to eq 0
+              result = run_rscons(rsconscript: "custom_config_check.rb", op: "build")
+              expect(result.stderr).to eq ""
+              expect(result.stdout).to match /GREP_WORKAROUND/
+              expect(result.status).to eq 0
+            end
+          end
+        end
+
+        context "when the custom logic indicates success" do
+          it "passes configuration with the correct message" do
+            test_dir "configure"
+            create_exe "grep", "echo 'grep (GNU grep) 3.0'"
+            result = run_rscons(rsconscript: "custom_config_check.rb", op: "configure")
+            expect(result.stderr).to eq ""
+            expect(result.stdout).to match /Checking 'grep' version\.\.\. good!/
+            expect(result.status).to eq 0
+            result = run_rscons(rsconscript: "custom_config_check.rb", op: "build")
+            expect(result.stderr).to eq ""
+            expect(result.stdout).to match /GREP_FULL/
+            expect(result.status).to eq 0
+          end
+        end
+      end
+    end
+
     it "does everything" do
       test_dir "configure"
       create_exe "pkg-config", "echo '-DMYPACKAGE'"