diff --git a/ChangeLog b/ChangeLog
index dd8a3144b..cb1058948 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,8 @@
+2006-04-06  Adam Jackson  <ajax@freedesktop.org>
+
+	* hw/dmx/dmxextension.c:
+	Coverity #1037: Sanity check idx before use.
+
 2006-04-06  Adam Jackson  <ajax@freedesktop.org>
 
 	* Makefile.am:
diff --git a/hw/dmx/dmxextension.c b/hw/dmx/dmxextension.c
index feadb5e31..24f796954 100644
--- a/hw/dmx/dmxextension.c
+++ b/hw/dmx/dmxextension.c
@@ -1062,8 +1062,8 @@ static Bool dmxCompareScreens(DMXScreenInfo *new, DMXScreenInfo *old)
 /** Reattach previously detached back-end screen. */
 int dmxAttachScreen(int idx, DMXScreenAttributesPtr attr)
 {
-    ScreenPtr      pScreen   = screenInfo.screens[idx];
-    DMXScreenInfo *dmxScreen = &dmxScreens[idx];
+    ScreenPtr      pScreen;
+    DMXScreenInfo *dmxScreen;
     CARD32         scrnNum   = idx;
     DMXScreenInfo  oldDMXScreen;
     int            i;
@@ -1083,6 +1083,8 @@ int dmxAttachScreen(int idx, DMXScreenAttributesPtr attr)
 
     /* Cannot add a screen that does not exist */
     if (idx < 0 || idx >= dmxNumScreens) return 1;
+    pScreen = screenInfo.screens[idx];
+    dmxScreen = &dmxScreens[idx];
 
     /* Cannot attach to a screen that is already opened */
     if (dmxScreen->beDisplay) {