diff --git a/src/include/rpc/clnt.h b/src/include/rpc/clnt.h
index b2fc7e27..7767d4ca 100644
--- a/src/include/rpc/clnt.h
+++ b/src/include/rpc/clnt.h
@@ -134,7 +134,7 @@ typedef struct __rpc_client {
 		void		(*cl_destroy) __P((struct __rpc_client *));
 		/* the ioctl() of rpc */
 		bool_t          (*cl_control) __P((struct __rpc_client *, u_int,
-				    char *));
+				    void *));
 	} *cl_ops;
 	caddr_t			cl_private;	/* private stuff */
 } CLIENT;