--- freeglut-3.2.1.orig/src/fg_gl2.h	2012-04-21 20:22:24.000000000 +0200
+++ freeglut-3.2.1/src/fg_gl2.h	2021-11-02 10:29:44.673793670 +0100
@@ -67,13 +67,13 @@ typedef void (APIENTRY *FGH_PFNGLENABLEV
 typedef void (APIENTRY *FGH_PFNGLDISABLEVERTEXATTRIBARRAYPROC) (GLuint);
 typedef void (APIENTRY *FGH_PFNGLVERTEXATTRIBPOINTERPROC) (GLuint index, GLint size, GLenum type, GLboolean normalized, GLsizei stride, const GLvoid *pointer);
 
-FGH_PFNGLGENBUFFERSPROC fghGenBuffers;
-FGH_PFNGLDELETEBUFFERSPROC fghDeleteBuffers;
-FGH_PFNGLBINDBUFFERPROC fghBindBuffer;
-FGH_PFNGLBUFFERDATAPROC fghBufferData;
-FGH_PFNGLENABLEVERTEXATTRIBARRAYPROC fghEnableVertexAttribArray;
-FGH_PFNGLDISABLEVERTEXATTRIBARRAYPROC fghDisableVertexAttribArray;
-FGH_PFNGLVERTEXATTRIBPOINTERPROC fghVertexAttribPointer;
+extern FGH_PFNGLGENBUFFERSPROC fghGenBuffers;
+extern FGH_PFNGLDELETEBUFFERSPROC fghDeleteBuffers;
+extern FGH_PFNGLBINDBUFFERPROC fghBindBuffer;
+extern FGH_PFNGLBUFFERDATAPROC fghBufferData;
+extern FGH_PFNGLENABLEVERTEXATTRIBARRAYPROC fghEnableVertexAttribArray;
+extern FGH_PFNGLDISABLEVERTEXATTRIBARRAYPROC fghDisableVertexAttribArray;
+extern FGH_PFNGLVERTEXATTRIBPOINTERPROC fghVertexAttribPointer;
 
 #    endif