diff --git a/lambda-test/airgate-test.c b/lambda-test/airgate-test.c
index 3e92ffb..6293d54 100644
--- a/lambda-test/airgate-test.c
+++ b/lambda-test/airgate-test.c
@@ -115,6 +115,11 @@
 static bool testIsDriverFault(void) {
 
 	setDriverFault(true);
+	setSleepMode(true);
+
+	assertFalse(isDriverFault());
+
+	setSleepMode(false);
 
 	assertTrue(isDriverFault());
 
diff --git a/lambda/airgate.c b/lambda/airgate.c
index 489391d..3483d7e 100644
--- a/lambda/airgate.c
+++ b/lambda/airgate.c
@@ -118,7 +118,7 @@
 }
 
 bool isDriverFault(void) {
-	return bit_is_clear(PIN, PIN_FAULT);
+	return bit_is_clear(PIN, PIN_FAULT) && bit_is_set(PORT, PIN_SLEEP);
 }
 
 void setSleepMode(bool const on) {