diff --git a/src/Visp.Compiler/Syntax/SynWriter.fs b/src/Visp.Compiler/Syntax/SynWriter.fs
index c7dedb4..9f51c5e 100644
--- a/src/Visp.Compiler/Syntax/SynWriter.fs
+++ b/src/Visp.Compiler/Syntax/SynWriter.fs
@@ -137,7 +137,10 @@ module Write =
     let newlineIndent: SynWriter -> unit = chain newline indent
 
     let lineof (w: SynWriter) (range: range) =
-        fmtprintfn w "// line %i @\"%s\"" range.StartLine range.FileName
+        if SyntaxWriteUtilThreadStatics.RunningTests then
+            fmtprintfn w "// line %i @\"%s\"" range.StartLine ((NormalizedPath range.FileName).Path)
+        else
+            fmtprintfn w "// line %i @\"%s\"" range.StartLine range.FileName
 
     let text (w: SynWriter) (txt: Text) =
         match txt with