diff --git a/include/knowrob/Printable.h b/include/knowrob/Printable.h
index 57d8cf6a2d..fe98d11e40 100644
--- a/include/knowrob/Printable.h
+++ b/include/knowrob/Printable.h
@@ -48,8 +48,9 @@ namespace knowrob {
 	}
 }
 
-	template <>
-	struct fmt::formatter<knowrob::Printable> : public fmt::formatter<std::string> {
+
+	template <typename Char>
+	struct fmt::formatter<knowrob::Printable, Char> : public fmt::formatter<std::string, Char> {
 		template <typename FormatContext>
 		constexpr auto format(const knowrob::Printable& p, FormatContext& ctx) const {
 			return fmt::format_to(ctx.out(), "{}", p.format());