diff --git a/src/demod/DemodulatorThread.cpp b/src/demod/DemodulatorThread.cpp
index 4c257bb..99b439b 100644
--- a/src/demod/DemodulatorThread.cpp
+++ b/src/demod/DemodulatorThread.cpp
@@ -1,7 +1,14 @@
-#include "DemodulatorThread.h"
 #include "CubicSDRDefs.h"
+#include "DemodulatorThread.h"
 #include <vector>
 
+#ifdef _WIN32
+#include <cmath>
+#ifndef M_PI
+#define M_PI        3.14159265358979323846
+#endif
+#endif
+
 #ifdef __APPLE__
 #include <pthread.h>
 #endif