diff --git a/openttd_vs80.vcproj b/openttd_vs80.vcproj
--- a/openttd_vs80.vcproj
+++ b/openttd_vs80.vcproj
@@ -477,6 +477,10 @@
 				>
 			</File>
 			<File
+				RelativePath=".\date.c"
+				>
+			</File>
+			<File
 				RelativePath=".\debug.c"
 				>
 			</File>
@@ -864,6 +868,10 @@
 				>
 			</File>
 			<File
+				RelativePath=".\date.h"
+				>
+			</File>
+			<File
 				RelativePath=".\debug.h"
 				>
 			</File>