diff --git a/uxnrepl.py b/uxnrepl.py
index 019c574..759e80d 100644
--- a/uxnrepl.py
+++ b/uxnrepl.py
@@ -1,7 +1,7 @@
 #!/usr/bin/python
 
 from os import system
-from subprocess import run
+from subprocess import run, TimeoutExpired
 from sys import stdin, stdout
 from tempfile import mkstemp
 
@@ -55,13 +55,13 @@ def execute(s, sandbox=None, timeout=2.0):
     try:
         res = run(['uxnasm', tmp_tal, tmp_rom], cwd=sandbox, capture_output=True, timeout=timeout)
     except TimeoutExpired:
-        return 'uxnasm: timed out'
+        return b'uxnasm: timed out'
     if res.returncode != 0:
         return res.stderr
     try:
         res = run(['uxncli', tmp_rom], cwd=sandbox, capture_output=True, timeout=timeout)
     except TimeoutExpired:
-        return 'uxncli: timed out'
+        return b'uxncli: timed out'
     return res.stdout
 
 def main():