diff --git a/.mailmap b/.mailmap
index 403e1132c7d0..241cbb05010e 100644
--- a/.mailmap
+++ b/.mailmap
@@ -34,6 +34,9 @@
 #
 #   ...
 #
+# If it fails, you may need to replace `python` by `python3`, here and below, if
+# you're on a system that still uses python2 by default.
+#
 # 3. Add a line to this file with that same name and email address like:
 #
 #   Joe Bloggs <joe@bloggs.com>
diff --git a/bin/mailmap_check.py b/bin/mailmap_check.py
index 36e71f413a03..89fd30dc0ee6 100755
--- a/bin/mailmap_check.py
+++ b/bin/mailmap_check.py
@@ -15,14 +15,14 @@
 
 import sys
 import os
+if sys.version_info < (3, 8):
+    sys.exit("This script requires Python 3.8 or newer")
+
 from pathlib import Path
 from subprocess import run, PIPE
 from collections import OrderedDict, defaultdict
 from argparse import ArgumentParser
 
-if sys.version_info < (3, 8):
-    sys.exit("This script requires Python 3.8 or newer")
-
 def sympy_dir():
     return Path(__file__).resolve().parent.parent
 
@@ -304,7 +304,7 @@ def make_authors_file_lines(git_people):
         to their names are not found in the metadata of the git history. This
         file is generated automatically by running `./bin/authors_update.py`.
         """).lstrip()
-    header_extra = f"There are a total of {len(git_people)} authors."""
+    header_extra = "There are a total of %d authors."  % len(git_people)
     lines = header.splitlines()
     lines.append('')
     lines.append(header_extra)