1 files changed, 1 insertions, 0 deletions
diff --git a/src/PJ_geos.c b/src/PJ_geos.c
index f0a9bc24..2988e62e 100644
--- a/src/PJ_geos.c
+++ b/src/PJ_geos.c
@@ -31,6 +31,7 @@
 #include <errno.h>
 #include "proj.h"
 #include "projects.h"
+#include "proj_math.h"
 
 struct pj_opaque {
     double h;