diff --git a/alib2std/src/extensions/forward_tree.hpp b/alib2std/src/extensions/forward_tree.hpp
index 63d83983eb66f59f6d9ac6c4808505e3b401cff3..80482e62ceeba2f15efa9e1a5df2a5f31931a07e 100644
--- a/alib2std/src/extensions/forward_tree.hpp
+++ b/alib2std/src/extensions/forward_tree.hpp
@@ -33,24 +33,22 @@ public:
 		return m_children;
 	}
 
-	void nicePrint ( std::ostream & os, const std::string & prefix, const bool last ) const {
+	void nicePrint ( std::ostream & os, std::string prefix, const bool last ) const {
 		os << prefix;
 
-		std::string nextPrefix ( prefix );
-
 		if ( last ) {
 			os << "\\-";
-			nextPrefix += "  ";
+			prefix += "  ";
 		} else {
 			os << "|-";
-			nextPrefix += "| ";
+			prefix += "| ";
 		}
 
 		os << getData ( ) << std::endl;
 
 		for ( unsigned int i = 0; i < m_children.size ( ); ++i ) {
-			os << nextPrefix << "|" << std::endl;
-			m_children[i].nicePrint ( os, nextPrefix, i == m_children.size ( ) - 1 );
+			os << prefix << "|" << std::endl;
+			m_children[i].nicePrint ( os, prefix, i == m_children.size ( ) - 1 );
 		}
 	}
 
diff --git a/alib2std/src/extensions/tree.hpp b/alib2std/src/extensions/tree.hpp
index 13379c304b43b0d05972c8020a25fa0a123bdf1d..27ecb2285a0a50a788ea2eeb9ebe6ecf687387a7 100644
--- a/alib2std/src/extensions/tree.hpp
+++ b/alib2std/src/extensions/tree.hpp
@@ -42,24 +42,22 @@ public:
 		return m_children;
 	}
 
-	void nicePrint ( std::ostream & os, const std::string & prefix, const bool last ) const {
+	void nicePrint ( std::ostream & os, std::string prefix, const bool last ) const {
 		os << prefix;
 
-		std::string nextPrefix ( prefix );
-
 		if ( last ) {
 			os << "\\-";
-			nextPrefix += "  ";
+			prefix += "  ";
 		} else {
 			os << "|-";
-			nextPrefix += "| ";
+			prefix += "| ";
 		}
 
 		os << getData ( ) << std::endl;
 
 		for ( unsigned int i = 0; i < m_children.size ( ); ++i ) {
-			os << nextPrefix << "|" << std::endl;
-			m_children[i].nicePrint ( os, nextPrefix, i == m_children.size ( ) - 1 );
+			os << prefix << "|" << std::endl;
+			m_children[i].nicePrint ( os, prefix, i == m_children.size ( ) - 1 );
 		}
 	}
 
diff --git a/alib2std/src/forward_tree b/alib2std/src/forward_tree
index f3e395180b5752f089ba2dc5d75ca839a64f552d..10c1fbb67dd9221759666c4ef8fbfbfd84e412ff 100644
--- a/alib2std/src/forward_tree
+++ b/alib2std/src/forward_tree
@@ -11,5 +11,5 @@
 #include "extensions/tree_base.hpp"
 #include "extensions/forward_tree.hpp"
 
-#endif /* __TREE_HEADER_WRAPPER */
+#endif /* __TREE_HEADER_WRAPPER_ */
 
diff --git a/alib2std/src/tree b/alib2std/src/tree
index 0016f27b1ac405add0206a0c04ed6ce46f291907..c6794dd05382e5a98bcb0ef32c83911ed72928dc 100644
--- a/alib2std/src/tree
+++ b/alib2std/src/tree
@@ -11,5 +11,5 @@
 #include "extensions/tree_base.hpp"
 #include "extensions/tree.hpp"
 
-#endif /* __TREE_HEADER_WRAPPER */
+#endif /* __TREE_HEADER_WRAPPER_ */