diff --git a/include/GLFW/glfw3.h b/include/GLFW/glfw3.h
index ecbfd1d1..46f9ad4b 100644
--- a/include/GLFW/glfw3.h
+++ b/include/GLFW/glfw3.h
@@ -118,8 +118,8 @@ extern "C" {
 /* It is customary to use APIENTRY for OpenGL function pointer declarations on
  * all platforms.  Additionally, the Windows OpenGL header needs APIENTRY.
  */
-#ifndef APIENTRY
- #ifdef _WIN32
+#if !defined(APIENTRY)
+ #if defined(_WIN32)
   #define APIENTRY __stdcall
  #else
   #define APIENTRY