1 files changed, 3 insertions, 1 deletions
diff --git a/src/PJ_gstmerc.c b/src/PJ_gstmerc.c
index 81ec4e17..5b5109b0 100644
--- a/src/PJ_gstmerc.c
+++ b/src/PJ_gstmerc.c
@@ -1,5 +1,8 @@
 #define PJ_LIB__
+
 #include <errno.h>
+#include <math.h>
+
 #include "projects.h"
 
 PROJ_HEAD(gstmerc, "Gauss-Schreiber Transverse Mercator (aka Gauss-Laborde Reunion)")
@@ -67,4 +70,3 @@ PJ *PROJECTION(gstmerc) {
 
     return P;
 }
-