diff --git a/sio/executors/inwer.py b/sio/executors/inwer.py
index 9ed90ae..8cb8b4f 100644
--- a/sio/executors/inwer.py
+++ b/sio/executors/inwer.py
@@ -32,7 +32,7 @@ def _run_in_executor(environ, command, executor, **kwargs):
 
 
 def _run_inwer(environ, use_sandboxes=False):
-    command = [tempcwd('inwer')]
+    command = [tempcwd('inwer'), environ['in_file_name']]
     if use_sandboxes:
         executor = SupervisedExecutor()
     else:
@@ -49,6 +49,9 @@ def run(environ):
 
     ``in_file``: the file redirected to the program's stdin
 
+    ``in_file_name``: the name of the input file. It's passed to inwer as
+                        the second argument.
+
     ``use_sandboxes``: if this key equals ``True``, the program is executed
                      in the SupervisedExecutor, otherwise the UnsafeExecutor
                      is used