diff --git a/pulsar-broker/src/test/java/org/apache/pulsar/schema/SchemaTest.java b/pulsar-broker/src/test/java/org/apache/pulsar/schema/SchemaTest.java
index dab9d08ac143e..29b386eb7e748 100644
--- a/pulsar-broker/src/test/java/org/apache/pulsar/schema/SchemaTest.java
+++ b/pulsar-broker/src/test/java/org/apache/pulsar/schema/SchemaTest.java
@@ -658,9 +658,12 @@ public void testNullKeyValueProperty() throws PulsarAdminException, PulsarClient
         final Map<String, String> map = new HashMap<>();
         map.put("key", null);
         map.put(null, "value"); // null key is not allowed for JSON, it's only for test here
-        ((SchemaInfoImpl)Schema.INT32.getSchemaInfo()).setProperties(map);
 
-        final Consumer<Integer> consumer = pulsarClient.newConsumer(Schema.INT32).topic(topic)
+        // leave INT32 instance unchanged
+        final Schema<Integer> integerSchema = Schema.INT32.clone();
+        ((SchemaInfoImpl) integerSchema.getSchemaInfo()).setProperties(map);
+
+        final Consumer<Integer> consumer = pulsarClient.newConsumer(integerSchema).topic(topic)
                 .subscriptionName("sub")
                 .subscribe();
         consumer.close();