diff --git a/projects/openttd_vs90.vcproj b/projects/openttd_vs90.vcproj
--- a/projects/openttd_vs90.vcproj
+++ b/projects/openttd_vs90.vcproj
@@ -1708,6 +1708,10 @@
 				>
 			</File>
 			<File
+				RelativePath=".\..\src\os\windows\string_uniscribe.h"
+				>
+			</File>
+			<File
 				RelativePath=".\..\src\stringfilter_type.h"
 				>
 			</File>
@@ -4516,6 +4520,10 @@
 				>
 			</File>
 			<File
+				RelativePath=".\..\src\os\windows\string_uniscribe.cpp"
+				>
+			</File>
+			<File
 				RelativePath=".\..\src\os\windows\win32.cpp"
 				>
 			</File>