diff --git a/crates/mist-api/src/builder.mist b/crates/mist-api/src/builder.mist
index 598886e..ea1d8af 100644
--- a/crates/mist-api/src/builder.mist
+++ b/crates/mist-api/src/builder.mist
@@ -58,7 +58,7 @@ pub bool build(Vec<String> mut args, PathBuf root)
                             serde_json::from_str<rev_mapper::Mapping>(&map_str).expect("Failed to parse map file")
                         });
                         let mist_file = map.mist_path.strip_prefix(&root);
-                        let (_, rev_mapper::MistMap(line, column)) = map.find(&rev_mapper::RustMap(span.line_end, span.column_start)).expect("Unable to find mapping");
+                        let (_, rev_mapper::MistMap(line, column)) = map.find(&rev_mapper::RustMap(span.line_end, span.column_start)).unwrap_or_default();
                         let mist_msg = MistDiagnosticMessage {
                             message: format!("{}: {}",
                                 msg.message.message,
diff --git a/crates/mist-api/src/transpiler.mist b/crates/mist-api/src/transpiler.mist
index 1e86bf2..ba5a442 100644
--- a/crates/mist-api/src/transpiler.mist
+++ b/crates/mist-api/src/transpiler.mist
@@ -222,13 +222,16 @@ pub void transpile_file(PathBuf& path, str& source, PathBuf output_file, str& mo
             process::exit(1);
         }
     };
+    if let Some(parent) = output_file.parent() {
+        let _ = fs::create_dir_all(parent);
+    }
     let res = fs::write(&output_file, output);
     let output_file_map = output_file.with_extension("map.json");
     let res_map = fs::write(&output_file_map, serde_json::to_string(&gc.mapping).unwrap());
     if res_map.is_err() {
         eprintln!("error: failed to write mapping output {}\n  {}",
             output_file_map.display(),
-            res.as_ref().unwrap_err(),);
+            res_map.as_ref().unwrap_err(),);
     }
     if res.is_err() {
         eprintln!("error: failed to write output {}\n  {}",