diff --git a/RAPIDpy/gis/taudem.py b/RAPIDpy/gis/taudem.py
index 9866fcf..fed1f37 100644
--- a/RAPIDpy/gis/taudem.py
+++ b/RAPIDpy/gis/taudem.py
@@ -430,9 +430,9 @@ def dinfFlowDirection(self,
         self._run_mpi_cmd(cmd)
 
         #create projection files
-        self._add_prj_file(pit_filled_elevation_grid,
+        self._add_prj_file(self.pit_filled_elevation_grid,
                            flow_dir_grid)
-        self._add_prj_file(pit_filled_elevation_grid,
+        self._add_prj_file(self.pit_filled_elevation_grid,
                            slope_grid)
 
     def d8FlowDirection(self,