diff --git a/ChangeLog b/ChangeLog
index 2f84c120f0..1313d5c71a 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,9 @@
+Fri Jul 15 15:32:13 2016  NAKAMURA Usaku  <usa@ruby-lang.org>
+
+	* time.c (time_arg): it seems that this function sometimes causes SEGV
+	  on mswin CI, then force to prevent `vtm->subsecx` from GC.  this is
+	  experimental.
+
 Fri Jul 15 09:53:48 2016  Nobuyoshi Nakada  <nobu@ruby-lang.org>
 
 	* enc/unicode/case-folding.rb, tool/enc-unicode.rb: check if
diff --git a/time.c b/time.c
index 9f009b5a15..2d1ce38120 100644
--- a/time.c
+++ b/time.c
@@ -2591,6 +2591,7 @@ time_arg(int argc, VALUE *argv, struct vtm *vtm)
     }
 
     validate_vtm(vtm);
+    RB_GC_GUARD(vtm->subsecx);
 }
 
 static int