diff --git a/cores/arduino/wiring_analog.cpp b/cores/arduino/wiring_analog.cpp
index 118e5a56d..83e7d1a35 100644
--- a/cores/arduino/wiring_analog.cpp
+++ b/cores/arduino/wiring_analog.cpp
@@ -61,7 +61,7 @@ void analogWrite(pin_size_t pin, int val)
     return;
   }
 #ifdef DAC
-  for (int i=0; i<NUM_ANALOG_OUTPUTS; i++) {
+  for (unsigned int i=0; i<NUM_ANALOG_OUTPUTS; i++) {
     if (digitalPinToPinName(pin) == g_AAnalogOutPinDescription[i].name) {
       analogWriteDAC(digitalPinToPinName(pin), val, i);
       return;
@@ -142,4 +142,4 @@ void analogReadResolution(int bits)
 int getAnalogReadResolution()
 {
   return read_resolution;
-}
\ No newline at end of file
+}