diff --git a/test/functional/test_framework/test_node.py b/test/functional/test_framework/test_node.py
index 60ca9269a5..e122028ba0 100755
--- a/test/functional/test_framework/test_node.py
+++ b/test/functional/test_framework/test_node.py
@@ -519,7 +519,7 @@ class TestNode():
         self._raise_assertion_error('Expected messages "{}" does not partially match log:\n\n{}\n\n'.format(str(expected_msgs), print_log))
 
     @contextlib.contextmanager
-    def busy_wait_for_debug_log(self, expected_msgs, timeout=60):
+    def busy_wait_for_debug_log(self, expected_msgs, timeout=60, *, forbid_msgs=()):
         """
         Block until we see a particular debug log message fragment or until we exceed the timeout.
         Return:
@@ -536,6 +536,13 @@ class TestNode():
                 dl.seek(prev_size)
                 log = dl.read()
 
+            for msg in forbid_msgs:
+                if msg in log:
+                    print_log = " - " + "\n - ".join(log.decode("utf8", errors="replace").splitlines())
+                    self._raise_assertion_error(
+                        'Forbidden message "{}" partially matched log:\n\n{}\n\n'.format(
+                            str(msg), print_log))
+
             for expected_msg in expected_msgs:
                 if expected_msg not in log:
                     found = False