diff --git a/src/backend/executor/nodeModifyTable.c b/src/backend/executor/nodeModifyTable.c
index 24b4818d35..91bd0de28c 100644
--- a/src/backend/executor/nodeModifyTable.c
+++ b/src/backend/executor/nodeModifyTable.c
@@ -516,9 +516,11 @@ ExecInsert(ModifyTableState *mtstate,
 			 *
 			 * We loop back here if we find a conflict below, either during
 			 * the pre-check, or when we re-check after inserting the tuple
-			 * speculatively.
+			 * speculatively.  Better allow interrupts in case some bug makes
+			 * this an infinite loop.
 			 */
 	vlock:
+			CHECK_FOR_INTERRUPTS();
 			specConflict = false;
 			if (!ExecCheckIndexConstraints(slot, estate, &conflictTid,
 										   arbiterIndexes))