diff --git a/mypy/semanal.py b/mypy/semanal.py
index 790c0c6d96d7..c27b43f01e7c 100644
--- a/mypy/semanal.py
+++ b/mypy/semanal.py
@@ -2120,7 +2120,7 @@ def analyze_namedtuple_assign(self, s: AssignmentStmt) -> bool:
         """Check if s defines a namedtuple."""
         if isinstance(s.rvalue, CallExpr) and isinstance(s.rvalue.analyzed, NamedTupleExpr):
             return True  # This is a valid and analyzed named tuple definition, nothing to do here.
-        if len(s.lvalues) != 1 or not isinstance(s.lvalues[0], NameExpr):
+        if len(s.lvalues) != 1 or not isinstance(s.lvalues[0], (NameExpr, MemberExpr)):
             return False
         lvalue = s.lvalues[0]
         name = lvalue.name
@@ -2128,6 +2128,9 @@ def analyze_namedtuple_assign(self, s: AssignmentStmt) -> bool:
                                                                           self.is_func_scope())
         if not is_named_tuple:
             return False
+        if isinstance(s.lvalues[0], MemberExpr):
+            self.fail("NamedTuple type as an attribute is not supported", lvalue)
+            return False
         # Yes, it's a valid namedtuple, but defer if it is not ready.
         if not info:
             self.mark_incomplete(name, lvalue, becomes_typeinfo=True)
diff --git a/test-data/unit/pythoneval.test b/test-data/unit/pythoneval.test
index 1a3c778b4604..0341d96eaece 100644
--- a/test-data/unit/pythoneval.test
+++ b/test-data/unit/pythoneval.test
@@ -1453,3 +1453,15 @@ def f_suppresses() -> int:
 [out]
 _testUnreachableWithStdlibContextManagersNoStrictOptional.py:9: error: Statement is unreachable
 _testUnreachableWithStdlibContextManagersNoStrictOptional.py:15: error: Statement is unreachable
+
+[case testNamedTupleAtRunTime]
+from typing import NamedTuple
+
+class A:
+    def __init__(self) -> None:
+        self.b = NamedTuple('x', [('s', str), ('n', int)])
+
+reveal_type(A().b)
+[out]
+_testNamedTupleAtRunTime.py:5: error: NamedTuple type as an attribute is not supported
+_testNamedTupleAtRunTime.py:7: note: Revealed type is 'Any'