diff --git a/hw/vfb/InitOutput.c b/hw/vfb/InitOutput.c
index 0b320dfe5..5fb7f09a8 100644
--- a/hw/vfb/InitOutput.c
+++ b/hw/vfb/InitOutput.c
@@ -480,20 +480,21 @@ vfbInstallColormap(ColormapPtr pmap)
         prgb = xallocarray(entries, sizeof(xrgb));
         defs = xallocarray(entries, sizeof(xColorItem));
 
-        for (i = 0; i < entries; i++)
-            ppix[i] = i;
-        /* XXX truecolor */
-        QueryColors(pmap, entries, ppix, prgb, serverClient);
+        if (ppix && prgb && defs) {
+            for (i = 0; i < entries; i++)
+                ppix[i] = i;
+            /* XXX truecolor */
+            QueryColors(pmap, entries, ppix, prgb, serverClient);
 
-        for (i = 0; i < entries; i++) { /* convert xrgbs to xColorItems */
-            defs[i].pixel = ppix[i] & 0xff;     /* change pixel to index */
-            defs[i].red = prgb[i].red;
-            defs[i].green = prgb[i].green;
-            defs[i].blue = prgb[i].blue;
-            defs[i].flags = DoRed | DoGreen | DoBlue;
+            for (i = 0; i < entries; i++) { /* convert xrgbs to xColorItems */
+                defs[i].pixel = ppix[i] & 0xff;     /* change pixel to index */
+                defs[i].red = prgb[i].red;
+                defs[i].green = prgb[i].green;
+                defs[i].blue = prgb[i].blue;
+                defs[i].flags = DoRed | DoGreen | DoBlue;
+            }
+            (*pmap->pScreen->StoreColors) (pmap, entries, defs);
         }
-        (*pmap->pScreen->StoreColors) (pmap, entries, defs);
-
         free(ppix);
         free(prgb);
         free(defs);