diff --git a/src/json_ui.cc b/src/json_ui.cc
index 4691f609..b4c6528c 100644
--- a/src/json_ui.cc
+++ b/src/json_ui.cc
@@ -9,6 +9,7 @@
 #include "ranges.hh"
 #include "string_utils.hh"
 
+#include <cstdio>
 #include <utility>
 
 #include <unistd.h>