diff --git a/src/win/pipe.c b/src/win/pipe.c
index a784325c..2a949e79 100644
--- a/src/win/pipe.c
+++ b/src/win/pipe.c
@@ -85,7 +85,7 @@ 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-%u", ptr, GetCurrentProcessId());
+  snprintf(name, size, "\\\\?\\pipe\\uv\\%p-%lu", ptr, GetCurrentProcessId());
 }