diff --git a/openttd.dsp b/openttd.dsp
--- a/openttd.dsp
+++ b/openttd.dsp
@@ -626,6 +626,10 @@ SOURCE=.\newgrf.h
# End Source File
# Begin Source File
+SOURCE=.\newgrf_callbacks.h
+# End Source File
+# Begin Source File
+
SOURCE=.\newgrf_engine.h
# End Source File
# Begin Source File
diff --git a/openttd.vcproj b/openttd.vcproj
--- a/openttd.vcproj
+++ b/openttd.vcproj
@@ -492,6 +492,9 @@
RelativePath=".\newgrf.h">
+
+