diff --git a/projects/openttd_vs90.vcproj b/projects/openttd_vs90.vcproj
--- a/projects/openttd_vs90.vcproj
+++ b/projects/openttd_vs90.vcproj
@@ -1181,6 +1181,10 @@
 				>
 			</File>
 			<File
+				RelativePath=".\..\src\newgrf_debug.h"
+				>
+			</File>
+			<File
 				RelativePath=".\..\src\newgrf_engine.h"
 				>
 			</File>
@@ -1849,6 +1853,10 @@
 				>
 			</File>
 			<File
+				RelativePath=".\..\src\newgrf_debug_gui.cpp"
+				>
+			</File>
+			<File
 				RelativePath=".\..\src\newgrf_gui.cpp"
 				>
 			</File>