diff --git a/BaseLib/ConfigTree.h b/BaseLib/ConfigTree.h
index 74af7c88d34bbb4ab76e6656d29d49747999f500..4394a85d5be7ca7a71f8d0027445bc3753f49589 100644
--- a/BaseLib/ConfigTree.h
+++ b/BaseLib/ConfigTree.h
@@ -106,9 +106,9 @@ public:
     public:
         using Iterator = boost::property_tree::ptree::const_assoc_iterator;
 
-        explicit SubtreeIterator(Iterator it, std::string root,
+        explicit SubtreeIterator(Iterator const& it, std::string const& root,
                                  ConfigTree const& parent)
-            : _it(it), _tagname(std::move(root)), _parent(parent)
+            : _it(it), _tagname(root), _parent(parent)
         {}
 
         SubtreeIterator& operator++() {
@@ -180,9 +180,9 @@ public:
     public:
         using Iterator = boost::property_tree::ptree::const_assoc_iterator;
 
-        explicit ValueIterator(Iterator it, std::string root,
+        explicit ValueIterator(Iterator const& it, std::string const& root,
                                ConfigTree const& parent)
-            : _it(it), _tagname(std::move(root)), _parent(parent)
+            : _it(it), _tagname(root), _parent(parent)
         {}
 
         ValueIterator<ValueType>& operator++() {