diff --git a/unit_tests/engine_test_helper.h b/unit_tests/engine_test_helper.h
index a908a2bf5f..c4ea98f969 100644
--- a/unit_tests/engine_test_helper.h
+++ b/unit_tests/engine_test_helper.h
@@ -90,7 +90,7 @@ public:
 	void assertInjectorUpEvent(const char *msg, int eventIndex, efitimeus_t momentX, long injectorIndex);
 	void assertInjectorDownEvent(const char *msg, int eventIndex, efitimeus_t momentX, long injectorIndex);
 	// todo: open question if this is worth a helper method or should be inlined?
-	void assertRpm(int expectedRpm, const char *msg);
+	void assertRpm(int expectedRpm, const char *msg = "RPM");
 
 	int executeActions();
 	void moveTimeForwardMs(float deltaTimeMs);
diff --git a/unit_tests/tests/trigger/test_trigger_decoder.cpp b/unit_tests/tests/trigger/test_trigger_decoder.cpp
index 1777556e60..6ac08c7cea 100644
--- a/unit_tests/tests/trigger/test_trigger_decoder.cpp
+++ b/unit_tests/tests/trigger/test_trigger_decoder.cpp
@@ -98,7 +98,7 @@ TEST(trigger, test1995FordInline6TriggerDecoder) {
 
 	engine->periodicFastCallback();
 	eth.fireTriggerEvents(48);
-	eth.assertRpm(2000, "rpm");
+	eth.assertRpm(2000);
 	engine->periodicFastCallback();
 	eth.fireTriggerEvents(48);