diff --git a/src/RecastNavMesh.hpp b/src/RecastNavMesh.hpp
index ff43134..9ee04a3 100644
--- a/src/RecastNavMesh.hpp
+++ b/src/RecastNavMesh.hpp
@@ -20,7 +20,7 @@ namespace godot {
       bool m_calculated = false;
       rcConfig config;
       RecastPartitionType partition_type = WATERSHED;
-      rcHeightfield* m_heightfield;
+      rcHeightfield* m_heightfield = NULL;
     protected:
       static void _bind_methods();
     public: