diff --git a/lambda-test/Makefile b/lambda-test/Makefile
index 1ccaab4..8ae915a 100644
--- a/lambda-test/Makefile
+++ b/lambda-test/Makefile
@@ -22,7 +22,7 @@
 
 ## Link to directory of project under test and its source files
 TEST_SOURCE_DIR = /data/Job/git/lambda-avr/lambda/
-TEST_SOURCE_FILES = sensors.c
+TEST_SOURCE_FILES = sensors.c integers.c
 
 ##########------------------------------------------------------##########
 ##########                 Programmer Defaults                  ##########
diff --git a/lambda-test/lambda-test.c b/lambda-test/lambda-test.c
index 7cbf684..8131aad 100644
--- a/lambda-test/lambda-test.c
+++ b/lambda-test/lambda-test.c
@@ -26,12 +26,7 @@
 uint8_t testToLambdaInter(void) {
 	int16_t lambda = toLambda(50);
 
-	char buf[10];
-	snprintf(buf, 10, "%d", lambda);
-	printString(buf);
-
-	// should be 1073 (rounding)
-	return lambda == 1074;
+	return lambda == 1073;
 }
 
 uint8_t testToTempI(void) {
diff --git a/lambda/Makefile b/lambda/Makefile
index feaaa11..a8bc706 100644
--- a/lambda/Makefile
+++ b/lambda/Makefile
@@ -14,7 +14,7 @@
 
 ## If you've split your program into multiple .c / .h files, 
 ## include the additional source (in same directory) here 
-LOCAL_SOURCE = sensors.c
+LOCAL_SOURCE = sensors.c integers.c
 
 ## Here you can link to one more directory (and multiple .c files)
 EXTRA_SOURCE_DIR = /data/Work/AVR/AVR-Programming-master/AVR-Programming-Library/
diff --git a/lambda/integers.c b/lambda/integers.c
new file mode 100644
index 0000000..8d874a5
--- /dev/null
+++ b/lambda/integers.c
@@ -0,0 +1,15 @@
+/*
+ * integers.c
+ *
+ *  Created on: 07.03.2015
+ *      Author: dode@luniks.net
+ */
+#include <avr/io.h>
+#include "integers.h"
+
+int32_t roundNearest(int32_t num, int32_t den) {
+	return ((num < 0) ^ (den < 0)) ?
+			((num - den / 2) / den) :
+			((num + den / 2) / den);
+}
+
diff --git a/lambda/integers.h b/lambda/integers.h
new file mode 100644
index 0000000..0058661
--- /dev/null
+++ b/lambda/integers.h
@@ -0,0 +1,15 @@
+/*
+ * integers.h
+ *
+ *  Created on: 07.03.2015
+ *      Author: dode@luniks.net
+ */
+
+/**
+ * Divides the given numerator by the given denominator
+ * to the nearest int and returns it.
+ * http://stackoverflow.com/a/18067292/709426
+ */
+int32_t roundNearest(int32_t num, int32_t den);
+
+// char* toDecimalString(int32_t num, int32_t den);
diff --git a/lambda/lambda.c b/lambda/lambda.c
index d544686..9d9234e 100644
--- a/lambda/lambda.c
+++ b/lambda/lambda.c
@@ -7,7 +7,6 @@
  * TODO comments, attribution
  * TODO DIDR?
  * TODO string.h?
- * TODO round, ceil, floor?
  */
 #include <math.h>
 #include <stdio.h>
@@ -18,6 +17,7 @@
 #include <util/delay.h>
 #include "USART.h"
 #include "sensors.h"
+#include "integers.h"
 
 int16_t lambdaVoltageAvg = 0;
 int16_t tempIVoltageAvg = 0;
@@ -48,14 +48,13 @@
 	char line0[40];
 	char line1[40];
 	snprintf(line0, sizeof(line0), "Ti %3d C %d   To %3d C %d\r\n", tempI, tempIVoltage, tempO, tempOVoltage);
-	snprintf(line1, sizeof(line1), "L %d.%03d %d\r\n", lambdaT.quot, lambdaT.rem, lambdaVoltage);
+	snprintf(line1, sizeof(line1), "L %d.%03d %d\r\n", lambdaT.quot, abs(lambdaT.rem), lambdaVoltage);
 	printString(line0);
 	printString(line1);
 }
 
 int16_t average(int16_t voltage, int16_t average, uint8_t weight) {
-	// rounding up, assuming voltages are never negative
-	return (voltage + (average * weight) + weight) / (weight + 1);
+	return roundNearest(voltage + (average * weight) + weight, weight + 1);
 }
 
 void measure(void) {
diff --git a/lambda/sensors.c b/lambda/sensors.c
index 3faa907..457df80 100644
--- a/lambda/sensors.c
+++ b/lambda/sensors.c
@@ -11,9 +11,7 @@
 #include <avr/interrupt.h>
 #include <avr/sleep.h>
 #include "sensors.h"
-
-#include <stdio.h>
-#include "USART.h"
+#include "integers.h"
 
 // #define AREF_MV 4850
 #define AREF_MV 5000
@@ -80,8 +78,7 @@
 }
 
 int16_t toTempI(int16_t mV) {
-	// rounding, assuming voltages are never negative
-	int temp = (mV + 3) / 5;
+	int temp = roundNearest(mV, 5);
 
 	return temp;
 }
@@ -109,9 +106,8 @@
 
 	int16_t diffVoltage = table[i + 1].mV - table[i].mV;
 	int16_t diffValue = table[i + 1].value - table[i].value;
-	// TODO could do rounding here
 	int16_t value = table[i].value +
-			((int32_t)(mV - table[i].mV) * diffValue / diffVoltage);
+			roundNearest((int32_t)(mV - table[i].mV) * diffValue, diffVoltage);
 
 	return value;
 }