diff --git a/apps/openmw/mwstate/charactermanager.cpp b/apps/openmw/mwstate/charactermanager.cpp
index 91d728ae0..70e9f0925 100644
--- a/apps/openmw/mwstate/charactermanager.cpp
+++ b/apps/openmw/mwstate/charactermanager.cpp
@@ -3,6 +3,7 @@
 
 #include <sstream>
 #include <stdexcept>
+#include <cctype> // std::isalnum
 
 #include <boost/filesystem.hpp>