diff --git a/firmware/controllers/algo/advance_map.cpp b/firmware/controllers/algo/advance_map.cpp
index 5909c94605..a9f3927ad1 100644
--- a/firmware/controllers/algo/advance_map.cpp
+++ b/firmware/controllers/algo/advance_map.cpp
@@ -39,7 +39,7 @@ static Map3D<TRACTION_CONTROL_ETB_DROP_SIZE, TRACTION_CONTROL_ETB_DROP_SIZE, int
 /**
  * @return ignition timing angle advance before TDC
  */
-static angle_t getRunningAdvance(int rpm, float engineLoad) {
+angle_t getRunningAdvance(int rpm, float engineLoad) {
 	if (engineConfiguration->timingMode == TM_FIXED) {
 		return engineConfiguration->fixedTiming;
 	}
@@ -120,7 +120,7 @@ static angle_t getRunningAdvance(int rpm, float engineLoad) {
 	return advanceAngle;
 }
 
-static angle_t getAdvanceCorrections(float engineLoad) {
+angle_t getAdvanceCorrections(float engineLoad) {
 	auto iat = Sensor::get(SensorType::Iat);
 
 	if (!iat) {
@@ -151,7 +151,7 @@ static angle_t getAdvanceCorrections(float engineLoad) {
 /**
  * @return ignition timing angle advance before TDC for Cranking
  */
-static angle_t getCrankingAdvance(int rpm, float engineLoad) {
+angle_t getCrankingAdvance(int rpm, float engineLoad) {
 	// get advance from the separate table for Cranking
 	if (engineConfiguration->useSeparateAdvanceForCranking) {
 		return interpolate2d(rpm, config->crankingAdvanceBins, config->crankingAdvance);
diff --git a/firmware/controllers/algo/advance_map.h b/firmware/controllers/algo/advance_map.h
index 52c976a45f..5698457afb 100644
--- a/firmware/controllers/algo/advance_map.h
+++ b/firmware/controllers/algo/advance_map.h
@@ -15,6 +15,10 @@ angle_t getCylinderIgnitionTrim(size_t cylinderNumber, int rpm, float ignitionLo
  * this method is used to build default advance map
  */
 float getInitialAdvance(int rpm, float map, float advanceMax);
+// public only for unit tests
+angle_t getCrankingAdvance(int rpm, float engineLoad);
+angle_t getRunningAdvance(int rpm, float engineLoad);
+angle_t getAdvanceCorrections(float engineLoad);
 
 size_t getMultiSparkCount(int rpm);
 void initIgnitionAdvanceControl();
diff --git a/unit_tests/tests/ignition_injection/test_ignition_scheduling.cpp b/unit_tests/tests/ignition_injection/test_ignition_scheduling.cpp
index 8d6168d85a..a8b14505da 100644
--- a/unit_tests/tests/ignition_injection/test_ignition_scheduling.cpp
+++ b/unit_tests/tests/ignition_injection/test_ignition_scheduling.cpp
@@ -6,6 +6,7 @@
  */
 
 #include "pch.h"
+#include "defaults.h"
 #include "spark_logic.h"
 
 using ::testing::_;
@@ -148,3 +149,26 @@ TEST(ignition, CylinderTimingTrim) {
 	EXPECT_NEAR(engine->engineState.timingAdvance[2], unadjusted + 2, EPS4D);
 	EXPECT_NEAR(engine->engineState.timingAdvance[3], unadjusted + 4, EPS4D);
 }
+
+TEST(ignition, negativeAdvance) {
+	EngineTestHelper eth(engine_type_e::TEST_ENGINE);
+
+  int rpm = 0;
+  float load = 50;
+
+	engineConfiguration->fixedTiming = -13;
+	engineConfiguration->timingMode = TM_FIXED;
+	// run the ignition math
+	engine->periodicFastCallback();
+
+	eth.assertRpm(0);
+
+	ASSERT_EQ(DEFAULT_CRANKING_ANGLE, getCrankingAdvance(rpm, load));
+	ASSERT_EQ(-13, getRunningAdvance(rpm, load));
+	ASSERT_EQ(0, getAdvanceCorrections(load));
+	ASSERT_EQ(707, getAdvance(rpm, load));
+
+	ASSERT_NEAR(-603.72, engine->ignitionState.baseIgnitionAdvance, EPS4D);
+	ASSERT_NEAR(-603.72, engine->ignitionState.correctedIgnitionAdvance, EPS4D);
+}
+