diff --git a/reactos/lib/drivers/oskittcp/oskittcp/osenv.c b/reactos/lib/drivers/oskittcp/oskittcp/osenv.c
index d29fa5fa239..aa8d246c63f 100644
--- a/reactos/lib/drivers/oskittcp/oskittcp/osenv.c
+++ b/reactos/lib/drivers/oskittcp/oskittcp/osenv.c
@@ -41,5 +41,10 @@ void* oskit_bufio_create(int len)
 }
 void oskit_bufio_map(void *srcbuf, void**dstbuf, int off, int len)
 {
+#if DBG
+   if (off != 0)
+       panic("oskit_bufio_map: offset is non-zero");
+#endif
+
    *dstbuf = srcbuf;
 }