diff --git a/services/surfaceflinger/SurfaceFlinger.cpp b/services/surfaceflinger/SurfaceFlinger.cpp
index 0e5d602..2df279a 100644
--- a/services/surfaceflinger/SurfaceFlinger.cpp
+++ b/services/surfaceflinger/SurfaceFlinger.cpp
@@ -2381,9 +2381,21 @@
 }
 
 const Vector< sp<Layer> >&
-SurfaceFlinger::getLayerSortedByZForHwcDisplay(int disp) {
+SurfaceFlinger::getLayerSortedByZForHwcDisplay(int id) {
     // Note: mStateLock is held here
-    return getDisplayDevice( getBuiltInDisplay(disp) )->getVisibleLayersSortedByZ();
+    wp<IBinder> dpy;
+    for (size_t i=0 ; i<mDisplays.size() ; i++) {
+        if (mDisplays.valueAt(i)->getHwcDisplayId() == id) {
+            dpy = mDisplays.keyAt(i);
+            break;
+        }
+    }
+    if (dpy == NULL) {
+        ALOGE("getLayerSortedByZForHwcDisplay: invalid hwc display id %d", id);
+        // Just use the primary display so we have something to return
+        dpy = getBuiltInDisplay(DisplayDevice::DISPLAY_PRIMARY);
+    }
+    return getDisplayDevice(dpy)->getVisibleLayersSortedByZ();
 }
 
 bool SurfaceFlinger::startDdmConnection()
diff --git a/services/surfaceflinger/SurfaceFlinger.h b/services/surfaceflinger/SurfaceFlinger.h
index 1017560..f0e6deb 100644
--- a/services/surfaceflinger/SurfaceFlinger.h
+++ b/services/surfaceflinger/SurfaceFlinger.h
@@ -122,7 +122,7 @@
 
     // for debugging only
     // TODO: this should be made accessible only to HWComposer
-    const Vector< sp<Layer> >& getLayerSortedByZForHwcDisplay(int disp);
+    const Vector< sp<Layer> >& getLayerSortedByZForHwcDisplay(int id);
 
 private:
     friend class Client;