diff --git a/packages/foreignthon/src/foreignthon/cli.py b/packages/foreignthon/src/foreignthon/cli.py
index 6c8e953..b2b5e82 100644
--- a/packages/foreignthon/src/foreignthon/cli.py
+++ b/packages/foreignthon/src/foreignthon/cli.py
@@ -1,15 +1,13 @@
 from __future__ import annotations
 
-import runpy
 import sys
-import tempfile
 from pathlib import Path
 
 import click
 
 from . import __version__
 from .errors import activate
-from .transpiler import transpile_file
+from .transpiler import transpile_file, run_transpiled
 
 
 @click.group()
@@ -26,15 +24,13 @@ def main():
 def run(file: Path, lang: str | None, keep: bool):
     """Transpile and run a foreign-language Python file."""
     if lang:
-        # Inject shebang override so transpiler picks it up
         source = file.read_text(encoding="utf-8")
         if not source.startswith("# foreignthon:"):
             source = f"# foreignthon: {lang}\n" + source
-        file.write_text(source, encoding="utf-8")
+            file.write_text(source, encoding="utf-8")
 
     transpiled = transpile_file(file)
 
-    # Detect lang for error hook
     detected_lang = lang or _lang_from_file(file)
     activate(detected_lang)
 
@@ -43,17 +39,7 @@ def run(file: Path, lang: str | None, keep: bool):
         out_path.write_text(transpiled, encoding="utf-8")
         click.echo(f"Compiled: {out_path}")
 
-    # Write to a temp file and run it — runpy keeps __file__ correct
-    with tempfile.NamedTemporaryFile(
-        suffix=".py", mode="w", encoding="utf-8", delete=False
-    ) as tmp:
-        tmp.write(transpiled)
-        tmp_path = tmp.name
-
-    try:
-        runpy.run_path(tmp_path, run_name="__main__")
-    finally:
-        Path(tmp_path).unlink(missing_ok=True)
+    run_transpiled(file, transpiled)
 
 
 @main.command()
diff --git a/packages/foreignthon/src/foreignthon/transpiler.py b/packages/foreignthon/src/foreignthon/transpiler.py
index 9409448..8aeeabd 100644
--- a/packages/foreignthon/src/foreignthon/transpiler.py
+++ b/packages/foreignthon/src/foreignthon/transpiler.py
@@ -52,7 +52,7 @@ def transpile(source: str, lang_code: str) -> str:
 
 def transpile_file(path: Path) -> str:
     """
-    Detect language from file extension (.es.py → es),
+    Detect language from file extension (.es.py -> es),
     read the file, and return transpiled Python source.
     """
     lang_code = _detect_lang(path)
@@ -64,8 +64,33 @@ def transpile_file(path: Path) -> str:
     return transpile(source, lang_code)
 
 
+def run_transpiled(original_path: Path, transpiled: str) -> None:
+    """
+    Execute transpiled source while making tracebacks point
+    to the original .es.py file, not a temp file.
+    """
+    import linecache
+
+    filename = str(original_path.resolve())
+
+    # Register original source lines so traceback displays them correctly
+    original_lines = original_path.read_text(encoding="utf-8").splitlines(keepends=True)
+    linecache.cache[filename] = (
+        len(original_lines),
+        None,
+        original_lines,
+        filename,
+    )
+
+    # Compile with original filename — this is what sets it in the traceback
+    code = compile(transpiled, filename, "exec")
+
+    glob = {"__file__": filename, "__name__": "__main__"}
+    exec(code, glob)
+
+
 def _detect_lang(path: Path) -> str:
-    """Extract lang code from extension, e.g. script.es.py → es."""
+    """Extract lang code from extension, e.g. script.es.py -> es."""
     suffixes = path.suffixes  # e.g. ['.es', '.py']
     if len(suffixes) >= 2 and suffixes[-1] == ".py":
         return suffixes[-2].lstrip(".")