diff --git a/Lib/inspect.py b/Lib/inspect.py
index 1f1b7f9..c489502 100644
--- a/Lib/inspect.py
+++ b/Lib/inspect.py
@@ -238,7 +238,7 @@
 
 def isabstract(object):
     """Return true if the object is an abstract base class (ABC)."""
-    return isinstance(object, type) and object.__flags__ & TPFLAGS_IS_ABSTRACT
+    return bool(isinstance(object, type) and object.__flags__ & TPFLAGS_IS_ABSTRACT)
 
 def getmembers(object, predicate=None):
     """Return all members of an object as (name, value) pairs sorted by name.