diff --git a/src/time_zone_lookup.cc b/src/time_zone_lookup.cc
index 75ab65d..ddc48e7 100644
--- a/src/time_zone_lookup.cc
+++ b/src/time_zone_lookup.cc
@@ -45,6 +45,7 @@
 #include <wchar.h>
 #include <windows.globalization.h>
 #include <windows.h>
+#include <winstring.h>
 #endif
 #endif