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">
 			</File>
 			<File
+				RelativePath=".\newgrf_callbacks.h">
+			</File>
+			<File
 				RelativePath=".\newgrf_engine.h">
 			</File>
 			<File