diff --git a/src/protocol/ArgParser.cxx b/src/protocol/ArgParser.cxx
index 123182f72..72190d9de 100644
--- a/src/protocol/ArgParser.cxx
+++ b/src/protocol/ArgParser.cxx
@@ -23,6 +23,7 @@
 #include "Chrono.hxx"
 #include "util/NumberParser.hxx"
 
+#include <stdio.h>
 #include <stdlib.h>
 
 static inline ProtocolError