diff --git a/docs/changelog.rst b/docs/changelog.rst
index 5609430f..0ac50758 100644
--- a/docs/changelog.rst
+++ b/docs/changelog.rst
@@ -26,6 +26,7 @@ v0.3.1.dev0 (unreleased)
 * :gh:issue:`869` Continuous Integration tests now cover CentOS 6 & 8, Debian 9 & 11, Ubuntu 16.04 & 20.04
 * :gh:issue:`860` Add initial support for podman connection (w/o Ansible support yet)
 * :gh:issue:`873` `python -c ...` first stage no longer uses :py:mod:`platform`` to detect the macOS release
+* :gh:issue:`876` `python -c ...` first stage no longer contains tab characters, to reduce size
 
 
 v0.3.0 (2021-11-24)
diff --git a/mitogen/parent.py b/mitogen/parent.py
index 251aee66..44ff9aba 100644
--- a/mitogen/parent.py
+++ b/mitogen/parent.py
@@ -1467,7 +1467,7 @@ class Connection(object):
     def get_boot_command(self):
         source = inspect.getsource(self._first_stage)
         source = textwrap.dedent('\n'.join(source.strip().split('\n')[2:]))
-        source = source.replace('    ', '\t')
+        source = source.replace('    ', ' ')
         source = source.replace('CONTEXT_NAME', self.options.remote_name)
         preamble_compressed = self.get_preamble()
         source = source.replace('PREAMBLE_COMPRESSED_LEN',
diff --git a/preamble_size.py b/preamble_size.py
old mode 100644
new mode 100755
index f0d1e804..efb46eae
--- a/preamble_size.py
+++ b/preamble_size.py
@@ -1,3 +1,4 @@
+#!/usr/bin/env python
 """
 Print the size of a typical SSH command line and the bootstrap code sent to new
 contexts.