diff --git a/src/nm-auth-utils.c b/src/nm-auth-utils.c
index 49a931f153..808dfca23e 100644
--- a/src/nm-auth-utils.c
+++ b/src/nm-auth-utils.c
@@ -49,7 +49,7 @@ typedef struct {
 	CList auth_call_lst;
 	NMAuthChain *chain;
 	NMAuthManagerCallId *call_id;
-	char *permission;
+	char permission[];
 } AuthCall;
 
 /*****************************************************************************/
@@ -74,7 +74,6 @@ auth_call_free (AuthCall *call)
 	if (call->call_id)
 		nm_auth_manager_check_authorization_cancel (call->call_id);
 	c_list_unlink_stale (&call->auth_call_lst);
-	g_free (call->permission);
 	g_slice_free (AuthCall, call);
 }
 
@@ -274,6 +273,7 @@ nm_auth_chain_add_call (NMAuthChain *self,
 {
 	AuthCall *call;
 	NMAuthManager *auth_manager = nm_auth_manager_get ();
+	gsize l_p_1;
 
 	g_return_if_fail (self);
 	g_return_if_fail (self->subject);
@@ -283,11 +283,11 @@ nm_auth_chain_add_call (NMAuthChain *self,
 	nm_assert (   nm_auth_subject_is_unix_process (self->subject)
 	           || nm_auth_subject_is_internal (self->subject));
 
-	call = g_slice_new (AuthCall);
-	*call = (AuthCall) {
-		.chain      = self,
-		.permission = g_strdup (permission),
-	};
+	l_p_1 = strlen (permission) + 1;
+	call = g_malloc (sizeof (AuthCall) + l_p_1);
+	call->chain = self;
+	call->call_id = NULL;
+	memcpy (call->permission, permission, l_p_1);
 	c_list_link_tail (&self->auth_call_lst_head, &call->auth_call_lst);
 	call->call_id = nm_auth_manager_check_authorization (auth_manager,
 	                                                     self->subject,