diff --git a/kdc/default_config.c b/kdc/default_config.c
index 408cc9215..c4d9f51fd 100644
--- a/kdc/default_config.c
+++ b/kdc/default_config.c
@@ -42,6 +42,7 @@
 void
 krb5_kdc_default_config(krb5_kdc_configuration *config)
 {
+    memset(config, 0, sizeof(*config));
     config->require_preauth = TRUE;
     config->kdc_warn_pwexpire = 0;
     config->encode_as_rep_as_tgs_rep = FALSE; /* bug compatibility */