diff --git a/libs/gui/SurfaceTextureClient.cpp b/libs/gui/SurfaceTextureClient.cpp
index 718fe84..18a0c10 100644
--- a/libs/gui/SurfaceTextureClient.cpp
+++ b/libs/gui/SurfaceTextureClient.cpp
@@ -815,12 +815,16 @@
         ALOGW_IF(res, "failed locking buffer (handle = %p)",
                 backBuffer->handle);
 
-        mLockedBuffer = backBuffer;
-        outBuffer->width  = backBuffer->width;
-        outBuffer->height = backBuffer->height;
-        outBuffer->stride = backBuffer->stride;
-        outBuffer->format = backBuffer->format;
-        outBuffer->bits   = vaddr;
+        if (res != 0) {
+            err = INVALID_OPERATION;
+        } else {
+            mLockedBuffer = backBuffer;
+            outBuffer->width  = backBuffer->width;
+            outBuffer->height = backBuffer->height;
+            outBuffer->stride = backBuffer->stride;
+            outBuffer->format = backBuffer->format;
+            outBuffer->bits   = vaddr;
+        }
     }
     return err;
 }