diff --git a/Xext/shm.c b/Xext/shm.c
index 9c8beb27c..7ca027a90 100644
--- a/Xext/shm.c
+++ b/Xext/shm.c
@@ -481,7 +481,7 @@ doShmPutImage(DrawablePtr dst, GCPtr pGC,
 {
     PixmapPtr pPixmap;
 
-    if (format == ZPixmap || depth == 1) {
+    if (format == ZPixmap || (format == XYPixmap && depth == 1)) {
 	pPixmap = GetScratchPixmapHeader(dst->pScreen, w, h, depth,
 					 BitsPerPixel(depth),
 					 PixmapBytePad(w, depth),