--- lensfun-0.3.95/apps/lenstool/image.cpp.orig	2018-07-09 11:58:53.471838000 +0300
+++ lensfun-0.3.95/apps/lenstool/image.cpp	2018-07-09 12:00:44.889513300 +0300
@@ -23,6 +23,9 @@
 } 
 #define unlink _unlink
 #else
+#ifdef __MINGW32__
+#define _USE_MATH_DEFINES
+#endif
 #include <unistd.h>
 #include <math.h>
 #endif