diff --git a/src/vblank.c b/src/vblank.c
index ff83a9a7..a6d9e039 100644
--- a/src/vblank.c
+++ b/src/vblank.c
@@ -18,7 +18,6 @@
 #include <X11/Xutil.h>
 #include <pthread.h>
 
-#include "backend/gl/glx.h"
 #endif
 
 #include "compiler.h"
@@ -96,6 +95,8 @@ struct sgi_video_sync_thread_args {
 	pthread_cond_t start_cnd;
 };
 
+static PFNGLXWAITVIDEOSYNCSGIPROC glXWaitVideoSyncSGI;
+
 static bool check_sgi_video_sync_extension(Display *dpy, int screen) {
 	const char *glx_ext = glXQueryExtensionsString(dpy, screen);
 	const char *needle = "GLX_SGI_video_sync";