diff --git a/src/backend/commands/extension.c b/src/backend/commands/extension.c
index ed0691592ef..0eb0b316fc4 100644
--- a/src/backend/commands/extension.c
+++ b/src/backend/commands/extension.c
@@ -2788,7 +2788,7 @@ AlterExtensionNamespace(const char *extensionName, const char *newschema, Oid *o
 {
 	Oid			extensionOid;
 	Oid			nspOid;
-	Oid			oldNspOid = InvalidOid;
+	Oid			oldNspOid;
 	AclResult	aclresult;
 	Relation	extRel;
 	ScanKeyData key[2];
@@ -2871,6 +2871,9 @@ AlterExtensionNamespace(const char *extensionName, const char *newschema, Oid *o
 
 	objsMoved = new_object_addresses();
 
+	/* store the OID of the namespace to-be-changed */
+	oldNspOid = extForm->extnamespace;
+
 	/*
 	 * Scan pg_depend to find objects that depend directly on the extension,
 	 * and alter each one's schema.
@@ -2916,12 +2919,6 @@ AlterExtensionNamespace(const char *extensionName, const char *newschema, Oid *o
 												 nspOid,
 												 objsMoved);
 
-		/*
-		 * Remember previous namespace of first object that has one
-		 */
-		if (oldNspOid == InvalidOid && dep_oldNspOid != InvalidOid)
-			oldNspOid = dep_oldNspOid;
-
 		/*
 		 * If not all the objects had the same old namespace (ignoring any
 		 * that are not in namespaces), complain.