diff --git a/src/glx/drisw_glx.c b/src/glx/drisw_glx.c
index c0d1e85fdc4..d7658eaf7c1 100644
--- a/src/glx/drisw_glx.c
+++ b/src/glx/drisw_glx.c
@@ -874,6 +874,7 @@ check_xshm(Display *dpy)
 
    shm_cookie = xcb_query_extension(c, 7, "MIT-SHM");
    shm_reply = xcb_query_extension_reply(c, shm_cookie, NULL);
+   xshm_opcode = shm_reply->major_opcode;
 
    has_mit_shm = shm_reply->present;
    free(shm_reply);