diff --git a/gfx/gl/GLContextProvider.h b/gfx/gl/GLContextProvider.h
--- a/gfx/gl/GLContextProvider.h
+++ b/gfx/gl/GLContextProvider.h
@@ -21,16 +21,18 @@ namespace gl {
 
 #define IN_GL_CONTEXT_PROVIDER_H
 
 // Null is always there
 #define GL_CONTEXT_PROVIDER_NAME GLContextProviderNull
 #include "GLContextProviderImpl.h"
 #undef GL_CONTEXT_PROVIDER_NAME
 
+#if !defined(MOZ_GL_PROVIDER)
+
 #ifdef XP_WIN
   #define GL_CONTEXT_PROVIDER_NAME GLContextProviderWGL
   #include "GLContextProviderImpl.h"
   #undef GL_CONTEXT_PROVIDER_NAME
   #define GL_CONTEXT_PROVIDER_DEFAULT GLContextProviderWGL
   #define DEFAULT_IMPL WGL
 #endif
 
@@ -59,23 +61,27 @@ namespace gl {
 #define GL_CONTEXT_PROVIDER_NAME GLContextProviderEAGL
 #include "GLContextProviderImpl.h"
 #undef GL_CONTEXT_PROVIDER_NAME
 #ifndef GL_CONTEXT_PROVIDER_DEFAULT
 #define GL_CONTEXT_PROVIDER_DEFAULT GLContextProviderEAGL
 #endif
 #endif
 
+#else //defined(MOZ_GL_PROVIDER)
+
 #ifdef MOZ_GL_PROVIDER
   #define GL_CONTEXT_PROVIDER_NAME MOZ_GL_PROVIDER
   #include "GLContextProviderImpl.h"
   #undef GL_CONTEXT_PROVIDER_NAME
   #define GL_CONTEXT_PROVIDER_DEFAULT MOZ_GL_PROVIDER
 #endif
 
+#endif
+
 #ifdef GL_CONTEXT_PROVIDER_DEFAULT
   typedef GL_CONTEXT_PROVIDER_DEFAULT GLContextProvider;
 #else
   typedef GLContextProviderNull GLContextProvider;
 #endif
 
 #undef IN_GL_CONTEXT_PROVIDER_H