diff --git a/test/threads/hb-shape-threads.cc b/test/threads/hb-shape-threads.cc
index 96dff3441..6bdd78d36 100644
--- a/test/threads/hb-shape-threads.cc
+++ b/test/threads/hb-shape-threads.cc
@@ -1,4 +1,5 @@
 #include <cassert>
+#include <cstdio>
 #include <cstring>
 #include <thread>
 #include <condition_variable>