diff --git a/kernel/include/process.h b/kernel/include/process.h
index 9d0c743e..b3f5f7a1 100644
--- a/kernel/include/process.h
+++ b/kernel/include/process.h
@@ -282,7 +282,7 @@ void check_need_resched(void);
 void cpu_set(int cpu, cpu_set_t *cpu_set, ihk_spinlock_t *lock);
 void cpu_clear(int cpu, cpu_set_t *cpu_set, ihk_spinlock_t *lock);
 
-struct process *findthread_and_lock(int pid, int tid, void *savelock, unsigned long *irqstate);
+struct process *findthread_and_lock(int pid, int tid, ihk_spinlock_t **savelock, unsigned long *irqstate);
 void process_unlock(void *savelock, unsigned long irqstate);
 
 #endif
diff --git a/kernel/process.c b/kernel/process.c
index c6430c43..012a809e 100644
--- a/kernel/process.c
+++ b/kernel/process.c
@@ -2066,7 +2066,7 @@ void runq_del_proc(struct process *proc, int cpu_id)
 }
 
 struct process *
-findthread_and_lock(int pid, int tid, void *savelock, unsigned long *irqstate)
+findthread_and_lock(int pid, int tid, ihk_spinlock_t **savelock, unsigned long *irqstate)
 {
 	struct cpu_local_var *v;
 	struct process *p;
@@ -2075,11 +2075,11 @@ findthread_and_lock(int pid, int tid, void *savelock, unsigned long *irqstate)
 
 	for(i = 0; i < num_processors; i++){
 		v = get_cpu_local_var(i);
-		*(ihk_spinlock_t **)savelock = &(v->runq_lock);
+		*savelock = &(v->runq_lock);
 		*irqstate = ihk_mc_spinlock_lock(&(v->runq_lock));
 		list_for_each_entry(p, &(v->runq), sched_list){
 			if(p->pid == pid &&
-			   p->tid == tid){
+			   (tid == -1 || p->tid == tid)){
 				return p;
 			}
 		}
diff --git a/kernel/procfs.c b/kernel/procfs.c
index e7ddb73d..08acf7c0 100644
--- a/kernel/procfs.c
+++ b/kernel/procfs.c
@@ -200,7 +200,7 @@ void process_procfs_request(unsigned long rarg)
 	int rosnum, ret, pid, tid, ans = -EIO, eof = 0;
 	char *buf, *p;
 	struct ihk_ikc_channel_desc *syscall_channel;
-	void *savelock;
+	ihk_spinlock_t *savelock;
 	unsigned long irqstate;
 
 	dprintf("process_procfs_request: invoked.\n");