diff --git a/src/lib.rs b/src/lib.rs
index 81f835e..b60cfe9 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -102,7 +102,7 @@ fn parse_input(token_stream: TokenStream) -> Result<WgslModuleMacroInput, Error>
         .next()
         .ok_or(Error::from_message("Expected single string literal."))?;
 
-    let source_dir = token.span().source_file().path().parent().unwrap().into();
+    let source_dir = Path::new(&token.span().local_file().unwrap()).parent().unwrap().into();
     let literal: LitStr = parse(token_stream)?;
     let filename = std::path::Path::new(&literal.value()).into();
     Ok(WgslModuleMacroInput {