diff --git a/src/backend/catalog/pg_enum.c b/src/backend/catalog/pg_enum.c
index fe61d4d..52c1271 100644
--- a/src/backend/catalog/pg_enum.c
+++ b/src/backend/catalog/pg_enum.c
@@ -28,6 +28,8 @@
 #include "utils/builtins.h"
 #include "utils/catcache.h"
 #include "utils/fmgroids.h"
+#include "utils/hsearch.h"
+#include "utils/memutils.h"
 #include "utils/syscache.h"
 #include "utils/tqual.h"
 
@@ -38,6 +40,9 @@ Oid			binary_upgrade_next_pg_enum_oid = InvalidOid;
 static void RenumberEnumType(Relation pg_enum, HeapTuple *existing, int nelems);
 static int	sort_order_cmp(const void *p1, const void *p2);
 
+/* hash table of values added in current transaction by AddEnumLabel */
+
+static HTAB *enum_blacklist = NULL;
 
 /*
  * EnumValuesCreate
@@ -460,8 +465,44 @@ restart:
 	heap_freetuple(enum_tup);
 
 	heap_close(pg_enum, RowExclusiveLock);
+
+	/* set up blacklist hash if required */
+	if (enum_blacklist == NULL)
+	{
+		HASHCTL     hash_ctl;
+		memset(&hash_ctl, 0, sizeof(hash_ctl));
+		hash_ctl.keysize = sizeof(Oid);
+		hash_ctl.entrysize = sizeof(Oid);
+		hash_ctl.hcxt = CurTransactionContext;
+		enum_blacklist = hash_create("Enum blacklist for current transaction",
+						   32,
+						   &hash_ctl,
+						   HASH_ELEM | HASH_BLOBS | HASH_CONTEXT);
+
+	}
+
+	/* and add the new value to the blacklist */
+
+	(void) hash_search(enum_blacklist, &newOid, HASH_ENTER, NULL);
 }
 
+bool
+EnumBlacklisted(Oid enum_id)
+{
+	bool found;
+
+	if (enum_blacklist == NULL)
+		return false;
+
+	(void) hash_search(enum_blacklist, &enum_id, HASH_FIND, &found);
+	return found;
+}
+
+void
+InitEnumBlacklist(void)
+{
+	enum_blacklist = NULL;
+}
 
 /*
  * RenameEnumLabel
diff --git a/src/backend/utils/adt/enum.c b/src/backend/utils/adt/enum.c
index 973397c..a7ba3d0 100644
--- a/src/backend/utils/adt/enum.c
+++ b/src/backend/utils/adt/enum.c
@@ -76,6 +76,10 @@ check_safe_enum_use(HeapTuple enumval_tup)
 		TransactionIdDidCommit(xmin))
 		return;
 
+	/* Check if the enum value is blacklisted. If not, it's safe */
+	if (! EnumBlacklisted(HeapTupleGetOid(enumval_tup)))
+		return;
+
 	/* It is a new enum value, so check to see if the whole enum is new */
 	en = (Form_pg_enum) GETSTRUCT(enumval_tup);
 	enumtyp_tup = SearchSysCache1(TYPEOID, ObjectIdGetDatum(en->enumtypid));
diff --git a/src/include/catalog/pg_enum.h b/src/include/catalog/pg_enum.h
index 5938ba5..f8a492b 100644
--- a/src/include/catalog/pg_enum.h
+++ b/src/include/catalog/pg_enum.h
@@ -69,5 +69,7 @@ extern void AddEnumLabel(Oid enumTypeOid, const char *newVal,
 			 bool skipIfExists);
 extern void RenameEnumLabel(Oid enumTypeOid,
 				const char *oldVal, const char *newVal);
+extern bool EnumBlacklisted(Oid enum_id);
+extern void InitEnumBlacklist(void);
 
 #endif							/* PG_ENUM_H */