diff --git a/src/build/mod.rs b/src/build/mod.rs
index d941635..309542f 100644
--- a/src/build/mod.rs
+++ b/src/build/mod.rs
@@ -398,7 +398,10 @@ impl<'a> FileBuilder<'a> {
                     Some(v) => v.clone(),
                     None => {
                         let mut b = self.clone_builder();
-                        b.eval_string(self.std.get(&def.path.fragment).unwrap())?;
+                        b.eval_input(
+                            OffsetStrIter::new(self.std.get(&def.path.fragment).unwrap())
+                                .with_src_file(&def.path.fragment),
+                        )?;
                         b.get_outputs_as_val()
                     }
                 };
diff --git a/src/iter.rs b/src/iter.rs
index 199c8d6..d8762f8 100644
--- a/src/iter.rs
+++ b/src/iter.rs
@@ -30,8 +30,8 @@ impl<'a> OffsetStrIter<'a> {
         }
     }
 
-    pub fn with_src_file(mut self, file: PathBuf) -> Self {
-        self.source_file = Some(file);
+    pub fn with_src_file<P: Into<PathBuf>>(mut self, file: P) -> Self {
+        self.source_file = Some(file.into());
         self
     }
 }