diff --git a/lambda-test/Makefile b/lambda-test/Makefile
index 76c37ca..b6451a1 100644
--- a/lambda-test/Makefile
+++ b/lambda-test/Makefile
@@ -14,8 +14,8 @@
 
 ## If you've split your program into multiple .c / .h files, 
 ## include the additional source (in same directory) here 
-LOCAL_SOURCE = avrjunit.c adc-test.c command-test.c display-test.c \
-integers-test.c interrupts-test.c sensors-test.c strings-test.c
+LOCAL_SOURCE = avrjunit.c adc-test.c alert-test.c command-test.c \
+display-test.c integers-test.c interrupts-test.c sensors-test.c strings-test.c
 
 ## Here you can link to one more directory (and multiple .c files)
 EXTRA_SOURCE_DIR = ../lambda/
diff --git a/lambda-test/alert-test.c b/lambda-test/alert-test.c
new file mode 100644
index 0000000..8d9c29b
--- /dev/null
+++ b/lambda-test/alert-test.c
@@ -0,0 +1,145 @@
+/*
+ * adc-test.c
+ *
+ * Unit tests for the lambda project.
+ *
+ *  Created on: 15.05.2015
+ *      Author: dode@luniks.net
+ *
+ */
+
+#include "avrjunit.h"
+#include "interrupts.h"
+#include "alert.h"
+
+/* Module alert */
+
+bool testOscillateBeep(void) {
+	extern uint8_t beepCount;
+	extern uint8_t oscCount;
+
+	beepCount = 0;
+	oscCount = 0;
+
+	// alert with two beep2 with a length of 2
+	alert(2, 2, "a", "b");
+	oscillateBeep();
+	oscillateBeep();
+
+	// beep on, alertActive true
+	assertTrue(beepCount == 2);
+	assertTrue(oscCount == 2);
+	assertTrue(bit_is_set(TCCR1A, COM1A0));
+	assertTrue(isAlertActive());
+
+	oscillateBeep();
+	oscillateBeep();
+
+	// beep off, alertActive still true
+	assertTrue(beepCount == 1);
+	assertTrue(oscCount == 0);
+	assertTrue(bit_is_clear(TCCR1A, COM1A0));
+	assertTrue(isAlertActive());
+
+	oscillateBeep();
+	oscillateBeep();
+
+	// beep on, alertActive still true
+	assertTrue(beepCount == 1);
+	assertTrue(oscCount == 2);
+	assertTrue(bit_is_set(TCCR1A, COM1A0));
+	assertTrue(isAlertActive());
+
+	oscillateBeep();
+	oscillateBeep();
+
+	// beep off, alertActive false
+	assertTrue(beepCount == 0);
+	assertTrue(oscCount == 0);
+	assertTrue(bit_is_clear(TCCR1A, COM1A0));
+	assertFalse(isAlertActive());
+
+	return true;
+}
+
+bool testBeep(void) {
+	extern uint8_t beepCount;
+	extern uint16_t beepLength;
+	extern uint8_t oscCount;
+
+	beepCount = 0;
+	beepLength = 0;
+	oscCount = 0;
+
+	beep(1, 2);
+
+	assertTrue(beepCount == 1);
+	assertTrue(beepLength == 2);
+	assertTrue(oscCount == 0);
+
+	return true;
+}
+
+bool testAlert(void) {
+	extern uint8_t beepCount;
+	extern uint16_t beepLength;
+	extern uint8_t oscCount;
+
+	beepCount = 0;
+	beepLength = 0;
+	oscCount = 0;
+
+	alert(1, 2, "a", "b");
+
+	assertTrue(beepCount == 1);
+	assertTrue(beepLength == 2);
+	assertTrue(oscCount == 0);
+	assertTrue(isAlertActive());
+
+	return true;
+}
+
+bool testCancelAlert(void) {
+	extern uint8_t beepCount;
+	extern uint16_t beepLength;
+	extern uint8_t oscCount;
+
+	beepCount = 0;
+	beepLength = 0;
+	oscCount = 0;
+
+	alert(1, 2, "a", "b");
+
+	assertTrue(beepCount == 1);
+	assertTrue(beepLength == 2);
+	assertTrue(oscCount == 0);
+	assertTrue(isAlertActive());
+
+	cancelAlert();
+
+	assertTrue(beepCount == 0);
+	assertTrue(oscCount == 0);
+	assertTrue(bit_is_clear(TCCR1A, COM1A0));
+	assertFalse(isAlertActive());
+
+	return true;
+}
+
+/* Test "class" */
+static const char class[] PROGMEM = "alert";
+
+/* Test names */
+static const char testOscillateBeep_P[] PROGMEM = "testOscillateBeep";
+static const char testBeep_P[] PROGMEM = "testBeep";
+static const char testAlert_P[] PROGMEM = "testAlert";
+static const char testCancelAlert_P[] PROGMEM = "testCancelAlert";
+
+/* Tests */
+static TestCase const tests[] = {
+		{class, testOscillateBeep_P, testOscillateBeep},
+		{class, testBeep_P, testBeep},
+		{class, testAlert_P, testAlert},
+		{class, testCancelAlert_P, testCancelAlert}
+};
+
+TestClass alertClass = {tests, sizeof(tests) / sizeof(tests[0])};
diff --git a/lambda-test/lambda-test.c b/lambda-test/lambda-test.c
index b0289d9..18272d8 100644
--- a/lambda-test/lambda-test.c
+++ b/lambda-test/lambda-test.c
@@ -24,6 +24,7 @@
 	initUSART();
 
 	extern TestClass adcClass;
+	extern TestClass alertClass;
 	extern TestClass commandClass;
 	extern TestClass displayClass;
 	extern TestClass integersClass;
@@ -33,6 +34,7 @@
 
 	beginSuite("lambda");
 	runClass(adcClass);
+	runClass(alertClass);
 	runClass(commandClass);
 	runClass(displayClass);
 	runClass(integersClass);
diff --git a/lambda/alert.c b/lambda/alert.c
index 87c6565..53d1264 100644
--- a/lambda/alert.c
+++ b/lambda/alert.c
@@ -17,12 +17,13 @@
 
 uint8_t beepCount = 0;
 uint16_t beepLength = 0;
+uint8_t oscCount = 0;
 
-static uint8_t oscCount = 0;
 static bool alertActive = false;
 
 void oscillateBeep(void) {
 	if (beepCount == 0) {
+		oscCount = 0;
 		return;
 	}
 	if (oscCount == 0) {
@@ -37,7 +38,7 @@
 			alertActive = false;
 		}
 	}
-	oscCount == beepLength * 2 ? oscCount = 0 : oscCount++;
+	oscCount == beepLength * 2 - 1 ? oscCount = 0 : oscCount++;
 }
 
 void beep(uint8_t const beeps, uint8_t const length) {
@@ -57,6 +58,7 @@
 
 void cancelAlert(void) {
 	beepCount = 0;
+	oscCount = 0;
 	// turn beep off
 	TCCR1A &= ~(1 << COM1A0);
 	alertActive = false;