diff --git a/inc/version.h b/inc/version.h
index 70d7cff..47df2cf 100644
--- a/inc/version.h
+++ b/inc/version.h
@@ -7,7 +7,7 @@
 #define VERSION_MAJOR    6
 #define VERSION_MINOR    0
 #define VERSION_BUILD    0
-#define VERSION_REVISION 3
+#define VERSION_REVISION 4
 
 #define VERSION          VERSION_MAJOR, VERSION_MINOR, VERSION_BUILD, VERSION_REVISION
 #define VERSION_STRING   ver_str(VERSION_MAJOR, VERSION_MINOR, VERSION_BUILD, VERSION_REVISION)
diff --git a/src/ddsurface.c b/src/ddsurface.c
index 09ade3b..cbea99f 100644
--- a/src/ddsurface.c
+++ b/src/ddsurface.c
@@ -972,6 +972,8 @@ HRESULT dds_Lock(
             lpDestRect->right > This->width ||
             lpDestRect->bottom > This->height)
         {
+            lpDDSurfaceDesc->lpSurface = NULL;
+
             return DDERR_INVALIDPARAMS;
         }