diff --git a/metrics_sdk/test/opentelemetry/sdk/metrics/meter_test.rb b/metrics_sdk/test/opentelemetry/sdk/metrics/meter_test.rb
index a9f9cb93c..31850eb2e 100644
--- a/metrics_sdk/test/opentelemetry/sdk/metrics/meter_test.rb
+++ b/metrics_sdk/test/opentelemetry/sdk/metrics/meter_test.rb
@@ -34,7 +34,7 @@
     it 'does not require advice' do
       instrument = meter.create_histogram('histogram', description: 'stuff', unit: 'things')
 
-      _(instrument.instance_variable_get(:@advice)).must_equal(nil)
+      assert_nil instrument.instance_variable_get(:@advice)
     end
   end