diff --git a/glx/glxserver.h b/glx/glxserver.h
index d9b106b82..1021aec80 100644
--- a/glx/glxserver.h
+++ b/glx/glxserver.h
@@ -97,7 +97,7 @@ struct __GLXprovider {
     const char *name;
     __GLXprovider *next;
 };
-__GLXprovider __glXDRISWRastProvider;
+extern __GLXprovider __glXDRISWRastProvider;
 
 void GlxPushProvider(__GLXprovider * provider);