diff --git a/src/graphviz_digraph_parser.cpp b/src/graphviz_digraph_parser.cpp
index 38c570e9..213ab1fe 100644
--- a/src/graphviz_digraph_parser.cpp
+++ b/src/graphviz_digraph_parser.cpp
@@ -62,9 +62,7 @@
 #include <sstream>
 #endif
 
-#ifndef GRAPHVIZ_GRAPH
-#error Need to define the GRAPHVIZ_GRAPH macro to either GraphvizGraph or GraphvizDigraph.
-#endif 
+#define GRAPHVIZ_GRAPH boost::GraphvizDigraph
 
 #define YYPARSE_PARAM g
 
diff --git a/src/graphviz_graph_parser.cpp b/src/graphviz_graph_parser.cpp
index b448eff5..f47d7046 100644
--- a/src/graphviz_graph_parser.cpp
+++ b/src/graphviz_graph_parser.cpp
@@ -62,9 +62,7 @@
 #include <sstream>
 #endif
 
-#ifndef GRAPHVIZ_GRAPH
-#error Need to define the GRAPHVIZ_GRAPH macro to either GraphvizGraph or GraphvizDigraph.
-#endif 
+#define GRAPHVIZ_GRAPH boost::GraphvizGraph
 
 #define YYPARSE_PARAM g