diff --git a/DDCore/src/BasicGrammarTypes.cpp b/DDCore/src/BasicGrammarTypes.cpp
index a9bd36ce56ea6096b73d9ed7a2ab234ab12f2192..6e97c8de48b547b4435e131be23c9146800b33db 100644
--- a/DDCore/src/BasicGrammarTypes.cpp
+++ b/DDCore/src/BasicGrammarTypes.cpp
@@ -60,6 +60,10 @@ DD4HEP_DEFINE_PARSER_GRAMMAR_TYPE(std::set<std::string>)
 typedef std::map<std::string, int> map_string_int;
 DD4HEP_DEFINE_PARSER_GRAMMAR(map_string_int,eval_obj)
 
+// e.g.,, runHeader map
+typedef std::map<std::string, std::string> map_string_string;
+DD4HEP_DEFINE_PARSER_GRAMMAR(map_string_string,eval_obj)
+
 DD4HEP_DEFINE_PARSER_GRAMMAR_CONT(ROOT::Math::XYZPoint,eval_obj)
 DD4HEP_DEFINE_PARSER_GRAMMAR_CONT(ROOT::Math::XYZVector,eval_obj)
 DD4HEP_DEFINE_PARSER_GRAMMAR_CONT(ROOT::Math::PxPyPzEVector,eval_obj)
diff --git a/DDG4/src/ComponentProperties.cpp b/DDG4/src/ComponentProperties.cpp
index fd4995cc99f93352ad92200eb209344f2df57dab..77f61dd5d66e6531d57a61766bb45eb29b7810ea 100644
--- a/DDG4/src/ComponentProperties.cpp
+++ b/DDG4/src/ComponentProperties.cpp
@@ -262,6 +262,9 @@ namespace DD4hep {
   typedef map<string, int> map_string_int;
   DD4HEP_DEFINE_PROPERTY_TYPE(map_string_int);
 
+  typedef map<string, string> map_string_string;
+  DD4HEP_DEFINE_PROPERTY_TYPE(map_string_string);
+
   // ROOT::Math Object instances
   DD4HEP_DEFINE_PROPERTY_TYPE(ROOT::Math::XYZPoint);
   DD4HEP_DEFINE_PROPERTY_TYPE(ROOT::Math::XYZVector);