diff --git a/Xext/xres.c b/Xext/xres.c
index a0734098c..b7933f251 100644
--- a/Xext/xres.c
+++ b/Xext/xres.c
@@ -28,6 +28,7 @@
 #include "misc.h"
 #include <string.h>
 #include "picturestr.h"
+#include "compint.h"
 
 /** @brief Holds fragments of responses for ConstructClientIds.
  *
@@ -342,6 +343,14 @@ ResFindPicturePixmaps(pointer value, XID id, pointer cdata)
 #endif
 }
 
+static void
+ResFindCompositeClientWindowPixmaps (pointer value, XID id, pointer cdata)
+{
+#ifdef COMPOSITE
+    ResFindResourcePixmaps(value, id, CompositeClientWindowType, cdata);
+#endif
+}
+
 static int
 ProcXResQueryClientPixmapBytes(ClientPtr client)
 {
@@ -384,7 +393,10 @@ ProcXResQueryClientPixmapBytes(ClientPtr client)
 #endif
 
 #ifdef COMPOSITE
-    /* FIXME: include composite pixmaps too */
+    /* Composite extension client window pixmaps. */
+    FindClientResourcesByType(clients[clientID], CompositeClientWindowType,
+                              ResFindCompositeClientWindowPixmaps,
+                              (pointer)(&bytes));
 #endif
 
     rep.type = X_Reply;
diff --git a/composite/compext.c b/composite/compext.c
index 940eed1fc..1d4d8bf97 100644
--- a/composite/compext.c
+++ b/composite/compext.c
@@ -497,6 +497,28 @@ SProcCompositeDispatch(ClientPtr client)
         return BadRequest;
 }
 
+/** @see GetDefaultBytes */
+static void
+GetCompositeClientWindowBytes(pointer value, XID id, ResourceSizePtr size)
+{
+    WindowPtr window = value;
+
+    /* Currently only pixmap bytes are reported to clients. */
+    size->resourceSize = 0;
+
+    /* Calculate pixmap reference sizes. */
+    size->pixmapRefSize = 0;
+    if (window->redirectDraw != RedirectDrawNone)
+    {
+        SizeType pixmapSizeFunc = GetResourceTypeSizeFunc(RT_PIXMAP);
+        ResourceSizeRec pixmapSize = { 0, 0 };
+        ScreenPtr screen = window->drawable.pScreen;
+        PixmapPtr pixmap = screen->GetWindowPixmap(window);
+        pixmapSizeFunc(pixmap, pixmap->drawable.id, &pixmapSize);
+        size->pixmapRefSize += pixmapSize.pixmapRefSize;
+    }
+}
+
 void
 CompositeExtensionInit(void)
 {
@@ -529,6 +551,9 @@ CompositeExtensionInit(void)
     if (!CompositeClientWindowType)
         return;
 
+    SetResourceTypeSizeFunc(CompositeClientWindowType,
+                            GetCompositeClientWindowBytes);
+
     CompositeClientSubwindowsType = CreateNewResourceType
         (FreeCompositeClientSubwindows, "CompositeClientSubwindows");
     if (!CompositeClientSubwindowsType)