diff --git a/include/REL/Version.h b/include/REL/Version.h
index ed12a035..66b0f8d4 100644
--- a/include/REL/Version.h
+++ b/include/REL/Version.h
@@ -222,7 +222,7 @@ template <class CharT>
 struct fmt::formatter<REL::Version, CharT> : formatter<std::string, CharT>
 {
 	template <class FormatContext>
-	auto format(const REL::Version& a_version, FormatContext& a_ctx)
+	auto format(const REL::Version& a_version, FormatContext& a_ctx) const
 	{
 		return formatter<std::string, CharT>::format(a_version.string(), a_ctx);
 	}