diff --git a/src/backend/access/common/reloptions.c b/src/backend/access/common/reloptions.c
index 4481d83412f..fab8294e732 100644
--- a/src/backend/access/common/reloptions.c
+++ b/src/backend/access/common/reloptions.c
@@ -517,6 +517,7 @@ static relopt_real realRelOpts[] =
 /* values from StdRdOptIndexCleanup */
 static relopt_enum_elt_def StdRdOptIndexCleanupValues[] =
 {
+	/* no value for NOT_SET */
 	{"auto", STDRD_OPTION_VACUUM_INDEX_CLEANUP_AUTO},
 	{"on", STDRD_OPTION_VACUUM_INDEX_CLEANUP_ON},
 	{"off", STDRD_OPTION_VACUUM_INDEX_CLEANUP_OFF},
@@ -557,7 +558,7 @@ static relopt_enum enumRelOpts[] =
 			ShareUpdateExclusiveLock
 		},
 		StdRdOptIndexCleanupValues,
-		STDRD_OPTION_VACUUM_INDEX_CLEANUP_AUTO,
+		STDRD_OPTION_VACUUM_INDEX_CLEANUP_NOT_SET,
 		gettext_noop("Valid values are \"on\", \"off\", and \"auto\".")
 	},
 	{
diff --git a/src/backend/commands/vacuum.c b/src/backend/commands/vacuum.c
index 6024bf2df31..64eed16a160 100644
--- a/src/backend/commands/vacuum.c
+++ b/src/backend/commands/vacuum.c
@@ -2210,20 +2210,25 @@ vacuum_rel(Oid relid, RangeVar *relation, VacuumParams params,
 		StdRdOptIndexCleanup vacuum_index_cleanup;
 
 		if (rel->rd_options == NULL)
-			vacuum_index_cleanup = STDRD_OPTION_VACUUM_INDEX_CLEANUP_AUTO;
+			vacuum_index_cleanup = STDRD_OPTION_VACUUM_INDEX_CLEANUP_NOT_SET;
 		else
 			vacuum_index_cleanup =
 				((StdRdOptions *) rel->rd_options)->vacuum_index_cleanup;
 
-		if (vacuum_index_cleanup == STDRD_OPTION_VACUUM_INDEX_CLEANUP_AUTO)
-			params.index_cleanup = VACOPTVALUE_AUTO;
-		else if (vacuum_index_cleanup == STDRD_OPTION_VACUUM_INDEX_CLEANUP_ON)
-			params.index_cleanup = VACOPTVALUE_ENABLED;
-		else
+		switch (vacuum_index_cleanup)
 		{
-			Assert(vacuum_index_cleanup ==
-				   STDRD_OPTION_VACUUM_INDEX_CLEANUP_OFF);
-			params.index_cleanup = VACOPTVALUE_DISABLED;
+			case STDRD_OPTION_VACUUM_INDEX_CLEANUP_ON:
+				params.index_cleanup = VACOPTVALUE_ENABLED;
+				break;
+			case STDRD_OPTION_VACUUM_INDEX_CLEANUP_OFF:
+				params.index_cleanup = VACOPTVALUE_DISABLED;
+				break;
+			case STDRD_OPTION_VACUUM_INDEX_CLEANUP_AUTO:
+				params.index_cleanup = VACOPTVALUE_AUTO;
+				break;
+			case STDRD_OPTION_VACUUM_INDEX_CLEANUP_NOT_SET:
+				params.index_cleanup = VACOPTVALUE_AUTO;
+				break;
 		}
 	}
 
diff --git a/src/include/utils/rel.h b/src/include/utils/rel.h
index ad7badf91da..41ab4586c6b 100644
--- a/src/include/utils/rel.h
+++ b/src/include/utils/rel.h
@@ -338,6 +338,7 @@ typedef enum StdRdOptIndexCleanup
 	STDRD_OPTION_VACUUM_INDEX_CLEANUP_AUTO = 0,
 	STDRD_OPTION_VACUUM_INDEX_CLEANUP_OFF,
 	STDRD_OPTION_VACUUM_INDEX_CLEANUP_ON,
+	STDRD_OPTION_VACUUM_INDEX_CLEANUP_NOT_SET,
 } StdRdOptIndexCleanup;
 
 typedef struct StdRdOptions