diff --git a/third_party/sike/fpx.c b/third_party/sike/fpx.c
index 92cb539d..b6936927 100644
--- a/third_party/sike/fpx.c
+++ b/third_party/sike/fpx.c
@@ -3,6 +3,7 @@
 *
 * Abstract: core functions over GF(p) and GF(p^2)
 *********************************************************************************************/
+#include <openssl/base.h>
 
 #include "utils.h"
 #include "fpx.h"