diff --git a/graphics/grOGL1.c b/graphics/grOGL1.c
index bf2bf3cb..355ba451 100644
--- a/graphics/grOGL1.c
+++ b/graphics/grOGL1.c
@@ -37,12 +37,12 @@
 
 GLubyte 	**grOGLStipples;
 HashTable	grOGLWindowTable;
-Display 	*grXdpy;
+extern Display 	*grXdpy; /* grX11thread.c */
 GLXContext	grXcontext;
-int		grXscrn;
-int		pipeRead, pipeWrite;
-int		Xhelper;
-Visual		*grVisual;
+extern int	grXscrn; /* grX11su1.c */
+extern int	pipeRead, pipeWrite; /* grX11su1.c */
+extern int	Xhelper; /* grX11su1.c */
+extern Visual	*grVisual; /* grX11su1.c */
 
 #ifdef HAVE_PTHREADS
 extern int writePipe;
diff --git a/graphics/grOGL5.c b/graphics/grOGL5.c
index f4ab4d0f..79c8a4d6 100644
--- a/graphics/grOGL5.c
+++ b/graphics/grOGL5.c
@@ -36,7 +36,7 @@ extern HashTable	grOGLWindowTable;
 extern Display *grXdpy;
 extern int	grXscrn;
 
-Cursor grCursors[MAX_CURSORS];
+extern Cursor grCursors[MAX_CURSORS]; /* grX11su5.c */
 
 
 /*
diff --git a/graphics/grX11su1.c b/graphics/grX11su1.c
index 68deaee7..f2efa4c9 100644
--- a/graphics/grX11su1.c
+++ b/graphics/grX11su1.c
@@ -52,7 +52,7 @@
 
 extern char  *DBWStyleType;
 
-Display      *grXdpy;
+extern Display *grXdpy; /* grX11thread.c */
 int	      grXscrn;
 Colormap      grXcmap;
 Visual       *grVisual;