diff --git a/ChangeLog b/ChangeLog
index fd73cda4b9..8269e6d74b 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,7 @@
+Sun Jul 10 08:57:20 2016  SHIBATA Hiroshi  <hsbt@ruby-lang.org>
+
+	* thread.c: Fixed implicit conversion error with Apple clang-800.0.31
+
 Sat Jul  9 12:43:09 2016  Shugo Maeda  <shugo@ruby-lang.org>
 
 	* lib/getoptlong.rb: use false instead of FALSE.
diff --git a/thread.c b/thread.c
index a53117ab82..023405bc89 100644
--- a/thread.c
+++ b/thread.c
@@ -1085,7 +1085,7 @@ getclockofday(struct timeval *tp)
 
     if (clock_gettime(CLOCK_MONOTONIC, &ts) == 0) {
 	tp->tv_sec = ts.tv_sec;
-	tp->tv_usec = ts.tv_nsec / 1000;
+	tp->tv_usec = (int)(ts.tv_nsec / 1000);
     }
     else
 #endif