Need to check for -1, not 0, to determine if shmat() failed

Signed-off-by: Alan Coopersmith <alan.coopersmith@oracle.com>

1 files changed, 1 insertions, 1 deletions

diff --git a/src/XvMC.c b/src/XvMC.c
index d97861f..736760b 100644
--- a/src/XvMC.c
+++ b/src/XvMC.c
@@ -526,7 +526,7 @@ Status XvMCGetDRInfo(Display *dpy, XvPortID port,
     if (shmKey >= 0) {
 	shMem = (CARD32 *) shmat(shmKey, NULL, 0);
 	shmctl(shmKey, IPC_RMID, NULL);
-	if ( shMem ) {
+	if (shMem != (void *) -1) {
 
 	    register volatile CARD32 *shMemC = shMem;
 	    register int i;