diff --git a/lib/cpp/test/DebugProtoTest.cpp b/lib/cpp/test/DebugProtoTest.cpp
index 26cc1ea..5649e18 100644
--- a/lib/cpp/test/DebugProtoTest.cpp
+++ b/lib/cpp/test/DebugProtoTest.cpp
@@ -17,6 +17,7 @@
  * under the License.
  */
 
+#define _USE_MATH_DEFINES
 #include <iostream>
 #include <cmath>
 #include "gen-cpp/DebugProtoTest_types.h"