diff --git a/mutmut/__main__.py b/mutmut/__main__.py
index 9e6bcad0..8af2b6ae 100644
--- a/mutmut/__main__.py
+++ b/mutmut/__main__.py
@@ -988,6 +988,8 @@ def s(key, default):
             result = [x for x in result.split("\n") if x]
         elif isinstance(default, int):
             result = int(result)
+        elif isinstance(default,bool):
+            result = result.lower() in ('1', 't', 'true')
         return result
     return s
 
@@ -1007,7 +1009,7 @@ def read_config():
             Path('tests.py'),
         ],
         max_stack_depth=s('max_stack_depth', -1),
-        debug=s('debug', 'False').lower() in ('1', 't', 'true'),
+        debug=s('debug', False),
     )