Index: src/lib/krb5/krb/princ_comp.c
===================================================================
--- src/lib/krb5/krb/princ_comp.c.orig
+++ src/lib/krb5/krb/princ_comp.c
@@ -33,6 +33,13 @@
 krb5_boolean KRB5_CALLCONV
 krb5_realm_compare(krb5_context context, krb5_const_principal princ1, krb5_const_principal princ2)
 {
+    if ((princ1 == NULL) || (princ2 == NULL))
+       return FALSE;
+
+    if ((krb5_princ_realm(context, princ1) == NULL) ||
+        (krb5_princ_realm(context, princ2) == NULL))
+       return FALSE;
+
     if (krb5_princ_realm(context, princ1)->length != 
 	krb5_princ_realm(context, princ2)->length ||
 	memcmp (krb5_princ_realm(context, princ1)->data, 
@@ -49,6 +56,9 @@ krb5_principal_compare(krb5_context cont
     register int i;
     krb5_int32 nelem;
 
+    if ((princ1 == NULL) || (princ2 == NULL))
+       return FALSE;
+
     nelem = krb5_princ_size(context, princ1);
     if (nelem != krb5_princ_size(context, princ2))
 	return FALSE;