diff --git a/examples/xkcd.cpp b/examples/xkcd.cpp
index 9bf6454..fa41cfc 100644
--- a/examples/xkcd.cpp
+++ b/examples/xkcd.cpp
@@ -1,6 +1,7 @@
+#define _USE_MATH_DEFINES
+#include <cmath>
 #include "../matplotlibcpp.h"
 #include <vector>
-#include <cmath>
 
 namespace plt = matplotlibcpp;