diff --git a/appl/xnlock/xnlock.c b/appl/xnlock/xnlock.c
index 4d6b8136e..46648f5aa 100644
--- a/appl/xnlock/xnlock.c
+++ b/appl/xnlock/xnlock.c
@@ -590,6 +590,8 @@ verify_krb5(const char *password)
 	    CREDENTIALS c;
 	    krb5_creds mcred, cred;
 
+	    krb5_cc_clear_mcred(&mcred);
+
 	    krb5_make_principal(context, &mcred.server,
 				client->realm,
 				"krbtgt",
diff --git a/lib/auth/afskauthlib/verify.c b/lib/auth/afskauthlib/verify.c
index 980d3ab47..a679bda4a 100644
--- a/lib/auth/afskauthlib/verify.c
+++ b/lib/auth/afskauthlib/verify.c
@@ -171,6 +171,8 @@ verify_krb5(struct passwd *pwd,
 	krb5_creds mcred, cred;
         krb5_realm realm;
 
+	krb5_cc_clear_mcred(&mcred);
+
         krb5_get_default_realm(context, &realm);
 	krb5_make_principal(context, &mcred.server, realm,
 			    "krbtgt",