diff --git a/tests/strings/strings.cpp b/tests/strings/strings.cpp
index 2731161702..37f13464cf 100644
--- a/tests/strings/strings.cpp
+++ b/tests/strings/strings.cpp
@@ -19,6 +19,8 @@
 
 #include "wx/private/localeset.h"
 
+#include <errno.h>
+
 // ----------------------------------------------------------------------------
 // test class
 // ----------------------------------------------------------------------------