double-quote-string-fixer
diff --git a/pre_commit_hooks/fix_encoding_pragma.py b/pre_commit_hooks/fix_encoding_pragma.py
index dbe9c6c..bde4e78 100644
--- a/pre_commit_hooks/fix_encoding_pragma.py
+++ b/pre_commit_hooks/fix_encoding_pragma.py
@@ -147,5 +147,5 @@
     return retv
 
 
-if __name__ == "__main__":
+if __name__ == '__main__':
     exit(main())
diff --git a/pre_commit_hooks/sort_simple_yaml.py b/pre_commit_hooks/sort_simple_yaml.py
index 3c8ef16..a381679 100755
--- a/pre_commit_hooks/sort_simple_yaml.py
+++ b/pre_commit_hooks/sort_simple_yaml.py
@@ -115,9 +115,9 @@
             new_lines = sort(lines)
 
             if lines != new_lines:
-                print("Fixing file `{filename}`".format(filename=filename))
+                print('Fixing file `{filename}`'.format(filename=filename))
                 f.seek(0)
-                f.write("\n".join(new_lines) + "\n")
+                f.write('\n'.join(new_lines) + '\n')
                 f.truncate()
                 retval = 1
 
diff --git a/pre_commit_hooks/trailing_whitespace_fixer.py b/pre_commit_hooks/trailing_whitespace_fixer.py
index b2b6418..2ccc003 100644
--- a/pre_commit_hooks/trailing_whitespace_fixer.py
+++ b/pre_commit_hooks/trailing_whitespace_fixer.py
@@ -69,7 +69,7 @@
     for ext in md_exts:
         if any(c in ext[1:] for c in r'./\:'):
             parser.error(
-                "bad --markdown-linebreak-ext extension {!r} (has . / \\ :)\n"
+                'bad --markdown-linebreak-ext extension {!r} (has . / \\ :)\n'
                 "  (probably filename; use '--markdown-linebreak-ext=EXT')"
                 .format(ext),
             )