diff --git a/src/backend/commands/vacuum.c b/src/backend/commands/vacuum.c
index 1fa71d11bcf..53aeb9ffcc4 100644
--- a/src/backend/commands/vacuum.c
+++ b/src/backend/commands/vacuum.c
@@ -447,7 +447,14 @@ vacuum(List *relations, VacuumParams *params,
 
 			if (params->options & VACOPT_VACUUM)
 			{
-				if (!vacuum_rel(vrel->oid, vrel->relation, params))
+				VacuumParams params_copy;
+
+				/*
+				 * vacuum_rel() scribbles on the parameters, so give it a copy
+				 * to avoid affecting other relations.
+				 */
+				memcpy(&params_copy, params, sizeof(VacuumParams));
+				if (!vacuum_rel(vrel->oid, vrel->relation, &params_copy))
 					continue;
 			}
 
@@ -1738,9 +1745,16 @@ vacuum_rel(Oid relid, RangeVar *relation, VacuumParams *params)
 	Oid			save_userid;
 	int			save_sec_context;
 	int			save_nestlevel;
+	VacuumParams toast_vacuum_params;
 
 	Assert(params != NULL);
 
+	/*
+	 * This function scribbles on the parameters, so make a copy early to
+	 * avoid affecting the TOAST table (if we do end up recursing to it).
+	 */
+	memcpy(&toast_vacuum_params, params, sizeof(VacuumParams));
+
 	/* Begin a transaction for vacuuming this relation */
 	StartTransactionCommand();
 
@@ -1967,7 +1981,7 @@ vacuum_rel(Oid relid, RangeVar *relation, VacuumParams *params)
 	 * totally unimportant for toast relations.
 	 */
 	if (toast_relid != InvalidOid)
-		vacuum_rel(toast_relid, NULL, params);
+		vacuum_rel(toast_relid, NULL, &toast_vacuum_params);
 
 	/*
 	 * Now release the session-level lock on the master table.