diff --git a/include/epoxy/gl.h b/include/epoxy/gl.h
index d389076..76634e3 100644
--- a/include/epoxy/gl.h
+++ b/include/epoxy/gl.h
@@ -43,12 +43,19 @@ extern "C" {
 #define __glext_h_
 #endif
 
+#define KHRONOS_SUPPORT_INT64   1
+#define KHRONOS_SUPPORT_FLOAT   1
+#define KHRONOS_APIATTRIBUTES
+
 #ifndef _WIN32
 /* APIENTRY and GLAPIENTRY are not used on Linux or Mac. */
 #define APIENTRY
 #define GLAPIENTRY
 #define EPOXYAPIENTRY
 #define GLAPI
+#define KHRONOS_APIENTRY
+#define KHRONOS_APICALL
+
 #else
 #ifndef APIENTRY
 #define APIENTRY __stdcall
@@ -65,6 +72,10 @@ extern "C" {
 #ifndef GLAPI
 #define GLAPI extern
 #endif
+
+#define KHRONOS_APIENTRY __stdcall
+#define KHRONOS_APICALL __declspec(dllimport) __stdcall
+
 #endif /* _WIN32 */
 
 #ifndef APIENTRYP