diff --git a/hw/xfree86/dri2/dri2.c b/hw/xfree86/dri2/dri2.c
index 6459f11..632e5fa 100644
--- a/hw/xfree86/dri2/dri2.c
+++ b/hw/xfree86/dri2/dri2.c
@@ -927,10 +927,23 @@ DRI2CanFlip(DrawablePtr pDraw)
 
     pWin = (WindowPtr) pDraw;
     pWinPixmap = pScreen->GetWindowPixmap(pWin);
-    if (pRootPixmap != pWinPixmap)
+    if (pRootPixmap != pWinPixmap) {
+        ErrorF("%s: Window pixmap != screen pixmap\n", __func__);
         return FALSE;
-    if (!RegionEqual(&pWin->clipList, &pRoot->winSize))
+    }
+    if (!RegionEqual(&pWin->clipList, &pRoot->winSize)) {
+        BoxPtr extents;
+
+        ErrorF("%s: Window clipList doesn't match root window dimensions:\n",
+               __func__);
+        extents = RegionExtents(&pWin->clipList);
+        ErrorF("Window clipList extents: (%d, %d)-(%d, %d)\n",
+               extents->x1, extents->y1, extents->x2, extents->y2);
+        extents = RegionExtents(&pRoot->winSize);
+        ErrorF("Root window extents:     (%d, %d)-(%d, %d)\n",
+               extents->x1, extents->y1, extents->x2, extents->y2);
         return FALSE;
+    }
 
     /* Does the window match the pixmap exactly? */
     if (pDraw->x != 0 || pDraw->y != 0 ||
@@ -938,8 +951,11 @@ DRI2CanFlip(DrawablePtr pDraw)
         pDraw->x != pWinPixmap->screen_x || pDraw->y != pWinPixmap->screen_y ||
 #endif
         pDraw->width != pWinPixmap->drawable.width ||
-        pDraw->height != pWinPixmap->drawable.height)
+        pDraw->height != pWinPixmap->drawable.height) {
+        ErrorF("%s: Window pixmap dimensions don't match window dimensions\n",
+               __func__);
         return FALSE;
+    }
 
     return TRUE;
 }