diff --git a/engines/e_nuron.c b/engines/e_nuron.c
index 4585dbed1f..d7960a9d95 100644
--- a/engines/e_nuron.c
+++ b/engines/e_nuron.c
@@ -57,6 +57,7 @@
  */
 
 #include <stdio.h>
+#include <string.h>
 #include <openssl/crypto.h>
 #include <openssl/buffer.h>
 #include <openssl/dso.h>