diff --git a/projection.c b/projection.cpp
similarity index 97%
rename from projection.c
rename to projection.cpp
index d1ca865..0009215 100644
--- a/projection.c
+++ b/projection.cpp
@@ -1,5 +1,8 @@
 #include <math.h>
-#include "projection.h"
+
+extern "C" {
+	#include "projection.h"
+}
 
 // http://wiki.openstreetmap.org/wiki/Slippy_map_tilenames
 void latlon2tile(double lat, double lon, int zoom, long long *x, long long *y) {