diff --git a/crypto/ecdh/ecdh.c b/crypto/ecdh/ecdh.c
index 6f9d0de..d4497f1 100644
--- a/crypto/ecdh/ecdh.c
+++ b/crypto/ecdh/ecdh.c
@@ -66,6 +66,8 @@
 
 #include <openssl/ecdh.h>
 
+#include <string.h>
+
 #include <openssl/bn.h>
 #include <openssl/digest.h>
 #include <openssl/err.h>