diff --git a/src/common/cmdline.cpp b/src/common/cmdline.cpp
index 0bfebc27b6..ffa7e5ba36 100644
--- a/src/common/cmdline.cpp
+++ b/src/common/cmdline.cpp
@@ -37,6 +37,7 @@
 #if wxUSE_CMDLINE_PARSER
 
 #include <ctype.h>
+#include <locale.h>             // for LC_ALL
 
 #include "wx/datetime.h"
 #include "wx/msgout.h"