diff --git a/alib2data/src/graph/directed/DirectedGraph.h b/alib2data/src/graph/directed/DirectedGraph.h
index c52be4f2556dd233f566b082145641d707e4bae6..3422c1135e20aad629402310e62b7d97afdeba01 100644
--- a/alib2data/src/graph/directed/DirectedGraph.h
+++ b/alib2data/src/graph/directed/DirectedGraph.h
@@ -18,7 +18,7 @@ class IDirectedGraph;
 class DirectedGraph : public std::acceptor<DirectedGraph, VisitableGraphBase, std::acceptor<DirectedGraph, alib::VisitableObjectBase, GraphBase>>
 {
 public:
-	explicit DirectedGraph(REPRESENTATION representation);
+	explicit DirectedGraph(REPRESENTATION representation = REPRESENTATION::ADJACENCY_LIST);
 	~DirectedGraph() noexcept;
 
 	DirectedGraph(const DirectedGraph &other);
diff --git a/alib2data/src/graph/undirected/UndirectedGraph.h b/alib2data/src/graph/undirected/UndirectedGraph.h
index 6c8bf430bdbef77db70e9112a39b5a886d6851cf..1eaf3433e382aa0f5122653b5455530c9880a4bd 100644
--- a/alib2data/src/graph/undirected/UndirectedGraph.h
+++ b/alib2data/src/graph/undirected/UndirectedGraph.h
@@ -18,7 +18,7 @@ class IUndirectedGraph;
 class UndirectedGraph : public std::acceptor<UndirectedGraph, VisitableGraphBase, std::acceptor<UndirectedGraph, alib::VisitableObjectBase, GraphBase>>
 {
 public:
-	explicit UndirectedGraph(REPRESENTATION representation);
+	explicit UndirectedGraph(REPRESENTATION representation = REPRESENTATION::ADJACENCY_LIST);
 	~UndirectedGraph() noexcept;
 
 	UndirectedGraph(const UndirectedGraph &other);