diff --git a/crypto/des/des_enc.c b/crypto/des/des_enc.c
index 828feba208af3ff066173f4b42919eccc29e4618..efe35aa3c589070ffc02db2798505fb220710edd 100644
--- a/crypto/des/des_enc.c
+++ b/crypto/des/des_enc.c
@@ -56,6 +56,7 @@
  * [including the GNU Public Licence.]
  */
 
+#include <openssl/crypto.h>
 #include "des_locl.h"
 #include "spr.h"