diff --git a/sdrbase/audio/audiocompressorsnd.h b/sdrbase/audio/audiocompressorsnd.h
index c2bd55322..712152db2 100644
--- a/sdrbase/audio/audiocompressorsnd.h
+++ b/sdrbase/audio/audiocompressorsnd.h
@@ -25,6 +25,7 @@
 #ifndef SDRBASE_AUDIO_AUDIOCOMPRESSORSND_H_
 #define SDRBASE_AUDIO_AUDIOCOMPRESSORSND_H_
 
+#define _USE_MATH_DEFINES
 #include <math.h>
 
 // maximum number of samples in the delay buffer