diff --git a/share/qtcreator/debugger/dumper.py b/share/qtcreator/debugger/dumper.py
index 01c359ffc0b..7d97f9e14c7 100644
--- a/share/qtcreator/debugger/dumper.py
+++ b/share/qtcreator/debugger/dumper.py
@@ -302,6 +302,8 @@ class DumperBase:
             'personaltypes',
         ]
 
+        self.currentQtNamespaceGuess = None
+
         # These values are never used, but the variables need to have
         # some value base for the swapping logic in Children.__enter__()
         # and Children.__exit__().