diff --git a/src/backend/commands/copy.c b/src/backend/commands/copy.c
index 110480f6eae..517660d3735 100644
--- a/src/backend/commands/copy.c
+++ b/src/backend/commands/copy.c
@@ -797,6 +797,8 @@ DoCopy(const CopyStmt *stmt, const char *queryString)
 
 	if (is_from)
 	{
+		Assert(rel);
+
 		/* check read-only transaction */
 		if (XactReadOnly && rel->rd_backend != MyBackendId)
 			PreventCommandIfReadOnly("COPY FROM");