diff --git a/src/CMakeLists.txt b/src/CMakeLists.txt
index 31cd9fd9..b5569c40 100644
--- a/src/CMakeLists.txt
+++ b/src/CMakeLists.txt
@@ -19,9 +19,9 @@ set(common_SOURCES error.c fullscreen.c gamma.c init.c input.c
                    joystick.c opengl.c time.c window.c)
 
 if(_GLFW_COCOA_NSGL)
-    set(libglfw_SOURCES ${common_SOURCES} cocoa_fullscreen.m cocoa_gamma.m
+    set(libglfw_SOURCES ${common_SOURCES} cocoa_fullscreen.m cocoa_gamma.c
                         cocoa_init.m cocoa_input.m cocoa_joystick.m
-                        cocoa_opengl.m cocoa_time.m cocoa_window.m)
+                        cocoa_opengl.m cocoa_time.c cocoa_window.m)
 
     # For some reason, CMake doesn't know about .m
     set_source_files_properties(${libglfw_SOURCES} PROPERTIES LANGUAGE C)
diff --git a/src/cocoa_gamma.m b/src/cocoa_gamma.c
similarity index 98%
rename from src/cocoa_gamma.m
rename to src/cocoa_gamma.c
index eb291082..53c47a89 100644
--- a/src/cocoa_gamma.m
+++ b/src/cocoa_gamma.c
@@ -32,6 +32,8 @@
 #include <limits.h>
 #include <string.h>
 
+#include <ApplicationServices/ApplicationServices.h>
+
 
 //************************************************************************
 //****                  GLFW internal functions                       ****
diff --git a/src/cocoa_time.m b/src/cocoa_time.c
similarity index 100%
rename from src/cocoa_time.m
rename to src/cocoa_time.c