diff --git a/src/backend/executor/nodeModifyTable.c b/src/backend/executor/nodeModifyTable.c
index d71c0a4322..9ff6bdd439 100644
--- a/src/backend/executor/nodeModifyTable.c
+++ b/src/backend/executor/nodeModifyTable.c
@@ -334,7 +334,8 @@ ExecComputeStoredGenerated(EState *estate, TupleTableSlot *slot, CmdType cmdtype
 			econtext = GetPerTupleExprContext(estate);
 			econtext->ecxt_scantuple = slot;
 
-			val = ExecEvalExpr(resultRelInfo->ri_GeneratedExprs[i], econtext, &isnull);
+			val = datumCopy(ExecEvalExpr(resultRelInfo->ri_GeneratedExprs[i], econtext, &isnull),
+							attr->attbyval, attr->attlen);
 
 			values[i] = val;
 			nulls[i] = isnull;