diff --git a/include/wx/string.h b/include/wx/string.h
index 05fc91a8ca..d4c054e71d 100644
--- a/include/wx/string.h
+++ b/include/wx/string.h
@@ -3921,6 +3921,11 @@ wxDEFINE_ALL_COMPARISONS(const char *, const wxCStrData&, wxCMP_CHAR_CSTRDATA)
 
 #if __cplusplus >= 201103L || wxCHECK_VISUALC_VERSION(10)
 
+// Don't do this if ToStdWstring() is not available. We could work around it
+// but, presumably, if using std::wstring is undesirable, then so is using
+// std::hash<> anyhow.
+#if wxUSE_STD_STRING
+
 #include <functional>
 
 namespace std
@@ -3935,6 +3940,8 @@ namespace std
     };
 } // namespace std
 
+#endif // wxUSE_STD_STRING
+
 #endif // C++11
 
 // ---------------------------------------------------------------------------