diff --git a/lib/krb5/crypto.c b/lib/krb5/crypto.c
index 65358d14f..fa5bd7cdc 100644
--- a/lib/krb5/crypto.c
+++ b/lib/krb5/crypto.c
@@ -4096,7 +4096,7 @@ krb5_string_to_key_derived(krb5_context context,
     struct encryption_type *et = _find_enctype(etype);
     krb5_error_code ret;
     struct key_data kd;
-    size_t keylen = et->keytype->bits / 8;
+    size_t keylen;
     u_char *tmp;
 
     if(et == NULL) {
@@ -4104,6 +4104,8 @@ krb5_string_to_key_derived(krb5_context context,
 			       etype);
 	return KRB5_PROG_ETYPE_NOSUPP;
     }
+    keylen = et->keytype->bits / 8;
+
     ALLOC(kd.key, 1);
     if(kd.key == NULL) {
 	krb5_set_error_string (context, "malloc: out of memory");