diff --git a/unit_tests/engine_test_helper.h b/unit_tests/engine_test_helper.h
index 1407c227e9..8fbfb30289 100644
--- a/unit_tests/engine_test_helper.h
+++ b/unit_tests/engine_test_helper.h
@@ -31,7 +31,13 @@ public:
 	void fireRise(int delayMs);
 	void fireFall(int delayMs);
 
+	/**
+	 * See also #fireRise()
+	 */
 	void firePrimaryTriggerRise();
+	/**
+	 * See also #fireFall()
+	 */
 	void firePrimaryTriggerFall();
 	void fireTriggerEvents(int count);
 	void fireTriggerEventsWithDuration(int delayMs);
diff --git a/unit_tests/tests/test_trigger_decoder.cpp b/unit_tests/tests/test_trigger_decoder.cpp
index 9ccd8d82a5..787ee8ed76 100644
--- a/unit_tests/tests/test_trigger_decoder.cpp
+++ b/unit_tests/tests/test_trigger_decoder.cpp
@@ -415,8 +415,7 @@ TEST(misc, testRpmCalculator) {
 	ASSERT_EQ( 0,  engine->executor.size()) << "queue size 7";
 	engine->executor.clear();
 
-	eth.moveTimeForwardUs(5000); // 5ms
-	eth.firePrimaryTriggerRise();
+	eth.fireRise(5 /*ms*/);
 	ASSERT_EQ( 4,  engine->executor.size()) << "queue size 8";
 	// todo: assert queue elements completely
 	assertEqualsM("8/0", start + 53333 - 1515, engine->executor.getForUnitTest(0)->momentX);