diff --git a/src/gui/chanOsc.cpp b/src/gui/chanOsc.cpp
index 24c25f4bd..7b0f8a027 100644
--- a/src/gui/chanOsc.cpp
+++ b/src/gui/chanOsc.cpp
@@ -17,6 +17,7 @@
  * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
  */
 
+#define _USE_MATH_DEFINES
 #include "gui.h"
 #include "../ta-log.h"
 #include "imgui.h"