diff --git a/src/backend/catalog/dependency.c b/src/backend/catalog/dependency.c
index c1212e9..7adc216 100644
--- a/src/backend/catalog/dependency.c
+++ b/src/backend/catalog/dependency.c
@@ -2037,6 +2037,15 @@ add_object_address(ObjectClass oclass, Oid objectId, int32 subId,
 {
 	ObjectAddress *item;
 
+	/*
+	 * Ensure object_classes is properly sized. Can't use OidIsValid here
+	 * because it's not marked as static (nor should it be).
+	 */
+	StaticAssertStmt(object_classes[MAX_OCLASS - 1] != 0,
+			"last OID in object_classes[] is invalid (did you forget to add a new entry to it?)");
+
+	Assert(OidIsValid(object_classes[oclass]));
+
 	/* enlarge array if needed */
 	if (addrs->numrefs >= addrs->maxrefs)
 	{
diff --git a/src/include/catalog/dependency.h b/src/include/catalog/dependency.h
index 5da18c2..515417d 100644
--- a/src/include/catalog/dependency.h
+++ b/src/include/catalog/dependency.h
@@ -149,6 +149,8 @@ typedef enum ObjectClass
 	OCLASS_EVENT_TRIGGER,		/* pg_event_trigger */
 	OCLASS_POLICY,				/* pg_policy */
 	OCLASS_TRANSFORM,			/* pg_transform */
+	
+	/* New classes need to be added to object_classes[] too. */
 	MAX_OCLASS					/* MUST BE LAST */
 } ObjectClass;