diff --git a/ChangeLog b/ChangeLog
index 3bbc89f579..617c26530c 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,8 @@
+Thu Nov 19 14:14:37 2015  NAKAMURA Usaku  <usa@ruby-lang.org>
+
+	* win32/win32.c (finish_overlapped_socket): return value of this
+	  function should be only 0 or SOCKET_ERROR.
+
 Thu Nov 19 14:12:12 2015  Nobuyoshi Nakada  <nobu@ruby-lang.org>
 
 	* compile.c (iseq_tailcall_optimize): apply tail call optimization
diff --git a/win32/win32.c b/win32/win32.c
index 6ebd9e433c..d6ffec6075 100644
--- a/win32/win32.c
+++ b/win32/win32.c
@@ -3269,15 +3269,17 @@ finish_overlapped_socket(BOOL input, SOCKET s, WSAOVERLAPPED *wol, int result, D
 		result = WSAGetOverlappedResult(s, wol, &size, TRUE, &flg)
 		);
 	    if (result) {
+		result = 0;
 		*len = size;
 		break;
 	    }
+	    result = SOCKET_ERROR;
 	    /* thru */
 	  default:
 	    if ((err = WSAGetLastError()) == WSAECONNABORTED && !input)
 		errno = EPIPE;
 	    else if (err == WSAEMSGSIZE && input) {
-		result = TRUE;
+		result = 0;
 		*len = size;
 		break;
 	    }