diff --git a/prometheus-metrics-core/src/test/java/io/prometheus/metrics/core/metrics/CounterTest.java b/prometheus-metrics-core/src/test/java/io/prometheus/metrics/core/metrics/CounterTest.java
index 89bc1699b..b13e50f8d 100644
--- a/prometheus-metrics-core/src/test/java/io/prometheus/metrics/core/metrics/CounterTest.java
+++ b/prometheus-metrics-core/src/test/java/io/prometheus/metrics/core/metrics/CounterTest.java
@@ -123,7 +123,7 @@ void testTotalStrippedFromName(String name) {
     assertThat(ProtobufUtil.shortDebugString(protobufData))
         .matches(
             "^name: \"my_counter_seconds_total\" type: COUNTER metric \\{ counter \\{ value: 0.0"
-                + " created_timestamp \\{ seconds: \\d+ nanos: \\d+ } } }$");
+                + " created_timestamp \\{ seconds: \\d+( nanos: \\d+)? } } }$");
   }
 
   @Test