diff --git a/Lib/multiprocessing/managers.py b/Lib/multiprocessing/managers.py
index fde0e40..8850258 100644
--- a/Lib/multiprocessing/managers.py
+++ b/Lib/multiprocessing/managers.py
@@ -410,7 +410,7 @@
             self.id_to_refcount[ident] -= 1
             if self.id_to_refcount[ident] == 0:
                 del self.id_to_obj[ident], self.id_to_refcount[ident]
-                util.debug('disposing of obj with id %d', ident)
+                util.debug('disposing of obj with id %r', ident)
         finally:
             self.mutex.release()
 
diff --git a/Misc/NEWS b/Misc/NEWS
index dc37a37..8f674c8 100644
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -376,6 +376,9 @@
 Library
 -------
 
+- Issue #6938: Fix a TypeError in string formatting of a multiprocessing
+  debug message.
+
 - Issue #6635: Fix profiler printing usage message.
 
 - Issue #6856: Add a filter keyword argument to TarFile.add().