diff --git a/mi/mioverlay.c b/mi/mioverlay.c
index 248f85ca3..c0cefe748 100644
--- a/mi/mioverlay.c
+++ b/mi/mioverlay.c
@@ -63,7 +63,6 @@ static DevPrivateKeyRec miOverlayScreenKeyRec;
 #define miOverlayScreenKey (&miOverlayScreenKeyRec)
 
 static void MarkUnderlayWindow(WindowPtr);
-static Bool CollectUnderlayChildrenRegions(WindowPtr, RegionPtr);
 
 #define MIOVERLAY_GET_SCREEN_PRIVATE(pScreen) ((miOverlayScreenPtr) \
 	dixLookupPrivate(&(pScreen)->devPrivates, miOverlayScreenKey))
@@ -171,63 +170,6 @@ miOverlayComputeCompositeClip(GCPtr pGC, WindowPtr pWin)
     }
 }
 
-Bool
-miOverlayCollectUnderlayRegions(WindowPtr pWin, RegionPtr *region)
-{
-    miOverlayTreePtr pTree = MIOVERLAY_GET_WINDOW_TREE(pWin);
-
-    if (pTree) {
-        *region = &pTree->borderClip;
-        return FALSE;
-    }
-
-    *region = RegionCreate(NullBox, 0);
-
-    CollectUnderlayChildrenRegions(pWin, *region);
-
-    return TRUE;
-}
-
-static Bool
-CollectUnderlayChildrenRegions(WindowPtr pWin, RegionPtr pReg)
-{
-    WindowPtr pChild;
-    miOverlayTreePtr pTree;
-    Bool hasUnderlay;
-
-    if (!(pChild = pWin->firstChild))
-        return FALSE;
-
-    hasUnderlay = FALSE;
-
-    while (1) {
-        if ((pTree = MIOVERLAY_GET_WINDOW_TREE(pChild))) {
-            RegionAppend(pReg, &pTree->borderClip);
-            hasUnderlay = TRUE;
-        }
-        else if (pChild->firstChild) {
-            pChild = pChild->firstChild;
-            continue;
-        }
-
-        while (!pChild->nextSib && (pWin != pChild))
-            pChild = pChild->parent;
-
-        if (pChild == pWin)
-            break;
-
-        pChild = pChild->nextSib;
-    }
-
-    if (hasUnderlay) {
-        Bool overlap;
-
-        RegionValidate(pReg, &overlap);
-    }
-
-    return hasUnderlay;
-}
-
 static void
 MarkUnderlayWindow(WindowPtr pWin)
 {
diff --git a/mi/mioverlay.h b/mi/mioverlay.h
index 40e9915b0..a16a51035 100644
--- a/mi/mioverlay.h
+++ b/mi/mioverlay.h
@@ -9,7 +9,6 @@
 typedef void (*miOverlayTransFunc) (ScreenPtr, int, BoxPtr);
 typedef Bool (*miOverlayInOverlayFunc) (WindowPtr);
 
-extern _X_EXPORT Bool miOverlayCollectUnderlayRegions(WindowPtr, RegionPtr *);
 extern _X_EXPORT void miOverlayComputeCompositeClip(GCPtr, WindowPtr);
 extern _X_EXPORT Bool miOverlayCopyUnderlay(ScreenPtr);
 extern _X_EXPORT void miOverlaySetTransFunction(ScreenPtr, miOverlayTransFunc);