diff --git a/compose_format/__init__.py b/compose_format/__init__.py
index d356c89..2167bde 100755
--- a/compose_format/__init__.py
+++ b/compose_format/__init__.py
@@ -77,7 +77,8 @@ def format(self, path, replace=False, strict=True):
 
     def format_string(self, data, replace=False, strict=True):
         data = self.reorder(load(data, RoundTripLoader), strict=strict)
-        formatted = dump(data, Dumper=RoundTripDumper, indent=2, width=120)
+        formatted = dump(data, Dumper=RoundTripDumper,
+                         indent=2, block_seq_indent=2, width=120)
 
         return formatted.strip() + '\n'
 
@@ -112,7 +113,7 @@ def fix_sexadecimal_numbers(value):
         import re
 
         SEXADECIMAL_NUMBER = '(?P<left>\d+):(?P<right>\d+)'
-        match = re.match(SEXADECIMAL_NUMBER, value)
+        match = re.match(SEXADECIMAL_NUMBER, str(value))
         if not match or int(match.group('left')) > 60 or int(match.group('right')) > 60:
             return value
         return SingleQuotedScalarString('{0}:{1}'.format(match.group('left'), match.group('right')))