diff --git a/tests/strings/strings.cpp b/tests/strings/strings.cpp
index 65ba92da1b..fd714aab82 100644
--- a/tests/strings/strings.cpp
+++ b/tests/strings/strings.cpp
@@ -19,6 +19,8 @@
 
 #include "wx/private/localeset.h"
 
+#include <errno.h>
+
 // ----------------------------------------------------------------------------
 // tests
 // ----------------------------------------------------------------------------