diff --git a/hw/dmx/dmxdpms.c b/hw/dmx/dmxdpms.c
index c4eb2232a..f3a167dcf 100644
--- a/hw/dmx/dmxdpms.c
+++ b/hw/dmx/dmxdpms.c
@@ -84,7 +84,7 @@ void dmxDPMSInit(DMXScreenInfo *dmxScreen)
         return;
     }
 
-    if (!dmxScreen->scrnWin != DefaultRootWindow (dmxScreen->beDisplay)) {
+    if (dmxScreen->scrnWin != DefaultRootWindow (dmxScreen->beDisplay)) {
         dmxLogOutput(dmxScreen,
 		     "Cannot use DPMS in window mode\n");
         return;