diff --git a/include/CLI/ConfigFwd.hpp b/include/CLI/ConfigFwd.hpp
index c5eda807..ba009ba6 100644
--- a/include/CLI/ConfigFwd.hpp
+++ b/include/CLI/ConfigFwd.hpp
@@ -8,6 +8,7 @@
 #include <iostream>
 #include <string>
 
+#include "CLI/Error.hpp"
 #include "CLI/StringTools.hpp"
 
 namespace CLI {