--- a/src/auth_passwd.c
+++ b/src/auth_passwd.c
@@ -43,7 +43,7 @@
 \* ---------------------------------------------------------------- */
 
 static struct passwd* pwd_entry = NULL;
-
+char * crypt (const char *key, const char *salt);
 static int alock_auth_passwd_init(const char* args) {
 
     errno = 0;