diff --git a/crypto/o_str.c b/crypto/o_str.c
index 8aadff5..ba427c9 100644
--- a/crypto/o_str.c
+++ b/crypto/o_str.c
@@ -385,7 +385,7 @@ int openssl_strerror_r(int errnum, char *buf, size_t buflen)
      * It can return a pointer to some (immutable) static string in which case
      * buf is left unused.
      */
-    err = strerror_r(errnum, buf, buflen);
+    err = (char *)strerror_r(errnum, buf, buflen);
     if (err == NULL || buflen == 0)
         return 0;
     /*