diff --git a/Xext/shape.c b/Xext/shape.c
index 670c44db33..f5076a70fa 100644
--- a/Xext/shape.c
+++ b/Xext/shape.c
@@ -33,6 +33,7 @@ in this Software without prior written authorization from The Open Group.
 
 #include "dix/dix_priv.h"
 #include "dix/gc_priv.h"
+#include "dix/rpcbuf_priv.h"
 #include "dix/window_priv.h"
 #include "miext/extinit_priv.h"
 #include "Xext/panoramiX.h"
@@ -938,8 +939,7 @@ ProcShapeGetRectangles(ClientPtr client)
 {
     REQUEST(xShapeGetRectanglesReq);
     WindowPtr pWin;
-    xRectangle *rects = NULL;
-    int nrects, i, rc;
+    int nrects, rc;
     RegionPtr region;
 
     REQUEST_SIZE_MATCH(xShapeGetRectanglesReq);
@@ -960,55 +960,56 @@ ProcShapeGetRectangles(ClientPtr client)
         client->errorValue = stuff->kind;
         return BadValue;
     }
+
+    struct x_rpcbuf rpcbuf = { .swapped = client->swapped, .err_clear = TRUE };
+
     if (!region) {
-        nrects = 1;
-        rects = calloc(1, sizeof(xRectangle));
-        if (!rects)
-            return BadAlloc;
+        xRectangle rect;
         switch (stuff->kind) {
         case ShapeBounding:
-            rects->x = -(int) wBorderWidth(pWin);
-            rects->y = -(int) wBorderWidth(pWin);
-            rects->width = pWin->drawable.width + wBorderWidth(pWin);
-            rects->height = pWin->drawable.height + wBorderWidth(pWin);
+            rect.x = -(int) wBorderWidth(pWin);
+            rect.y = -(int) wBorderWidth(pWin);
+            rect.width = pWin->drawable.width + wBorderWidth(pWin);
+            rect.height = pWin->drawable.height + wBorderWidth(pWin);
             break;
         case ShapeClip:
-            rects->x = 0;
-            rects->y = 0;
-            rects->width = pWin->drawable.width;
-            rects->height = pWin->drawable.height;
+            rect.x = 0;
+            rect.y = 0;
+            rect.width = pWin->drawable.width;
+            rect.height = pWin->drawable.height;
             break;
         case ShapeInput:
-            rects->x = -(int) wBorderWidth(pWin);
-            rects->y = -(int) wBorderWidth(pWin);
-            rects->width = pWin->drawable.width + wBorderWidth(pWin);
-            rects->height = pWin->drawable.height + wBorderWidth(pWin);
+            rect.x = -(int) wBorderWidth(pWin);
+            rect.y = -(int) wBorderWidth(pWin);
+            rect.width = pWin->drawable.width + wBorderWidth(pWin);
+            rect.height = pWin->drawable.height + wBorderWidth(pWin);
             break;
         }
+        nrects = 1;
+        x_rpcbuf_write_CARD16s(&rpcbuf, (CARD16*)&rect, 4);
     }
     else {
-        BoxPtr box;
-
         nrects = RegionNumRects(region);
-        box = RegionRects(region);
-        if (nrects) {
-            rects = calloc(nrects, sizeof(xRectangle));
-            if (!rects)
-                return BadAlloc;
-            for (i = 0; i < nrects; i++, box++) {
-                rects[i].x = box->x1;
-                rects[i].y = box->y1;
-                rects[i].width = box->x2 - box->x1;
-                rects[i].height = box->y2 - box->y1;
-            }
-        }
+        BoxPtr boxes = RegionRects(region);
+        for (int i=0; i < nrects; i++) {
+            xRectangle rect = {
+                .x = boxes[i].x1,
+                .y = boxes[i].y1,
+                .width = boxes[i].x2 - boxes[i].x1,
+                .height = boxes[i].y2 - boxes[i].y1,
+            };
+            x_rpcbuf_write_CARD16s(&rpcbuf, (CARD16*)&rect, 4);
+        };
     }
 
+    if (rpcbuf.error) /* buffer already cleared */
+        return BadAlloc;
+
     xShapeGetRectanglesReply rep = {
         .type = X_Reply,
         .ordering = YXBanded,
         .sequenceNumber = client->sequence,
-        .length = bytes_to_int32(nrects * sizeof(xRectangle)),
+        .length = x_rpcbuf_wsize_units(&rpcbuf),
         .nrects = nrects
     };
 
@@ -1016,11 +1017,9 @@ ProcShapeGetRectangles(ClientPtr client)
         swaps(&rep.sequenceNumber);
         swapl(&rep.length);
         swapl(&rep.nrects);
-        SwapShorts((short *) rects, (unsigned long) nrects * 4);
     }
     WriteToClient(client, sizeof(rep), &rep);
-    WriteToClient(client, nrects * sizeof(xRectangle), rects);
-    free(rects);
+    WriteRpcbufToClient(client, &rpcbuf);
     return Success;
 }