diff --git a/radio/src/audio_arm.h b/radio/src/audio_arm.h
index 54e351f6a..6926aa96b 100644
--- a/radio/src/audio_arm.h
+++ b/radio/src/audio_arm.h
@@ -55,7 +55,7 @@ template <unsigned int NUM_BITS> class BitField {
       return bits[bitNo >> 3] & (1 << (bitNo & 0x07));
     }
 
-    void getSize() const
+    unsigned int getSize() const
     {
       return NUM_BITS;
     }