diff --git a/extras/fixture/rakefile_helper.rb b/extras/fixture/rakefile_helper.rb
index 94a90be08b50d7b20e59af373f2c0c83d9836997..cad220ac137afb3e089dd86606853d6880af1990 100644
--- a/extras/fixture/rakefile_helper.rb
+++ b/extras/fixture/rakefile_helper.rb
@@ -6,10 +6,13 @@
 
 require 'yaml'
 require 'fileutils'
+require 'rbconfig'
 require_relative '../../auto/unity_test_summary'
 require_relative '../../auto/generate_test_runner'
 require_relative '../../auto/colour_reporter'
 
+$is_windows = (RbConfig::CONFIG['host_os'] =~ /mswin|mingw|cygwin/)
+
 C_EXTENSION = '.c'.freeze
 
 def load_configuration(config_file)
@@ -52,7 +55,12 @@ def build_compiler_fields
   defines = if $cfg['compiler']['defines']['items'].nil?
               ''
             else
-              squash($cfg['compiler']['defines']['prefix'], $cfg['compiler']['defines']['items'] + ['UNITY_OUTPUT_CHAR=UnityOutputCharSpy_OutputChar'] + ['UNITY_OUTPUT_CHAR_HEADER_DECLARATION=UnityOutputCharSpy_OutputChar(int)'])
+              if $is_windows
+                decl = 'UNITY_OUTPUT_CHAR_HEADER_DECLARATION=UnityOutputCharSpy_OutputChar(int)'
+              else
+                decl = 'UNITY_OUTPUT_CHAR_HEADER_DECLARATION=UnityOutputCharSpy_OutputChar\(int\)'
+              end
+              squash($cfg['compiler']['defines']['prefix'], $cfg['compiler']['defines']['items'] + ['UNITY_OUTPUT_CHAR=UnityOutputCharSpy_OutputChar'] + [decl])
             end
   options = squash('', $cfg['compiler']['options'])
   includes = squash($cfg['compiler']['includes']['prefix'], $cfg['compiler']['includes']['items'])
diff --git a/extras/fixture/test/Makefile b/extras/fixture/test/Makefile
index b8eef21165a309dc21b082dde59575c4e1d2b914..2560868d1c2b9679d10993cf3a809c5a62781f92 100644
--- a/extras/fixture/test/Makefile
+++ b/extras/fixture/test/Makefile
@@ -6,7 +6,11 @@ endif
 CFLAGS += -std=c99 -pedantic -Wall -Wextra -Werror
 CFLAGS += $(DEBUG)
 DEFINES = -D UNITY_OUTPUT_CHAR=UnityOutputCharSpy_OutputChar
-DEFINES += -D UNITY_OUTPUT_CHAR_HEADER_DECLARATION=UnityOutputCharSpy_OutputChar(int)
+ifeq ($(OS),Windows_NT)
+  DEFINES += -D UNITY_OUTPUT_CHAR_HEADER_DECLARATION=UnityOutputCharSpy_OutputChar(int)
+else
+  DEFINES += -D UNITY_OUTPUT_CHAR_HEADER_DECLARATION=UnityOutputCharSpy_OutputChar\(int\)
+endif
 SRC = ../src/unity_fixture.c \
       ../../../src/unity.c   \
       unity_fixture_Test.c   \