diff --git a/llarp/config/ini.cpp b/llarp/config/ini.cpp
index 8b626837b..886887656 100644
--- a/llarp/config/ini.cpp
+++ b/llarp/config/ini.cpp
@@ -1,6 +1,7 @@
 #include <config/ini.hpp>
 #include <util/logger.hpp>
 
+#include <cctype>
 #include <fstream>
 #include <list>
 #include <iostream>