diff --git a/src/video/mmx.h b/src/video/mmx.h
index 2f2093d18..e8fdcaf6a 100644
--- a/src/video/mmx.h
+++ b/src/video/mmx.h
@@ -353,7 +353,7 @@ mmx_ok(void)
 #define	mmx_m2r(op, mem, reg) \
 	__asm__ __volatile__ (#op " %0, %%" #reg \
 			      : /* nothing */ \
-			      : "X" (mem))
+			      : "m" (mem))
 
 #define	mmx_r2m(op, reg, mem) \
 	__asm__ __volatile__ (#op " %%" #reg ", %0" \