diff --git a/ttd.dsp b/ttd.dsp
--- a/ttd.dsp
+++ b/ttd.dsp
@@ -265,6 +265,10 @@ SOURCE=.\newgrf.c
 # End Source File
 
 # Begin Source File
+SOURCE=.\npf.c
+# End Source File
+
+# Begin Source File
 SOURCE=.\oldloader.c
 # End Source File
 
@@ -502,6 +506,10 @@ SOURCE=.\news.h
 # End Source File
 
 # Begin Source File
+SOURCE=.\npf.h
+# End Source File
+
+# Begin Source File
 SOURCE=.\pathfind.h
 # End Source File