1 files changed, 1 insertions, 0 deletions
diff --git a/src/PJ_eqdc.c b/src/PJ_eqdc.c
index f36e0518..5f65e7d0 100644
--- a/src/PJ_eqdc.c
+++ b/src/PJ_eqdc.c
@@ -2,6 +2,7 @@
 #include <errno.h>
 #include "proj.h"
 #include "projects.h"
+#include "proj_math.h"
 
 struct pj_opaque {
     double phi1;