diff --git a/src/win/pipe.c b/src/win/pipe.c
index bf98b776..08f0167d 100644
--- a/src/win/pipe.c
+++ b/src/win/pipe.c
@@ -70,7 +70,7 @@ static void eof_timer_close_cb(uv_handle_t* handle);
 
 
 static void uv_unique_pipe_name(char* ptr, char* name, size_t size) {
-  _snprintf(name, size, "\\\\.\\pipe\\uv\\%p-%d", ptr, GetCurrentProcessId());
+  _snprintf(name, size, "\\\\.\\pipe\\uv\\%p-%u", ptr, GetCurrentProcessId());
 }