diff --git a/mypy/messages.py b/mypy/messages.py
index 1d6641c00a61..4bafe85da0fc 100644
--- a/mypy/messages.py
+++ b/mypy/messages.py
@@ -1978,10 +1978,12 @@ def [T <: int] f(self, x: int, y: T) -> None
             s += ' = ...'
 
     # If we got a "special arg" (i.e: self, cls, etc...), prepend it to the arg list
-    if isinstance(tp.definition, FuncDef) and tp.definition.name is not None:
+    if (isinstance(tp.definition, FuncDef) and
+            tp.definition.name is not None and
+            tp.definition.arguments):
         definition_args = [arg.variable.name for arg in tp.definition.arguments]
-        if definition_args and tp.arg_names != definition_args \
-                and len(definition_args) > 0 and definition_args[0]:
+        if (tp.arg_names != definition_args and
+                definition_args[0]):
             if s:
                 s = ', ' + s
             s = definition_args[0] + s
diff --git a/mypy/nodes.py b/mypy/nodes.py
index abc8666e390d..f3e7fef34749 100644
--- a/mypy/nodes.py
+++ b/mypy/nodes.py
@@ -649,7 +649,7 @@ def set_line(self,
 class FuncItem(FuncBase):
     """Base class for nodes usable as overloaded function items."""
 
-    __slots__ = ('arguments',  # Note that can be None if deserialized (type is a lie!)
+    __slots__ = ('arguments',  # Note that can be empty if deserialized
                  'arg_names',  # Names of arguments
                  'arg_kinds',  # Kinds of arguments
                  'min_args',  # Minimum number of arguments
@@ -665,7 +665,7 @@ class FuncItem(FuncBase):
                  'expanded',  # Variants of function with type variables with values expanded
                  )
 
-    __deletable__ = ('arguments', 'max_pos', 'min_args')
+    __deletable__ = ('max_pos', 'min_args')
 
     def __init__(self,
                  arguments: Optional[List[Argument]] = None,
@@ -780,7 +780,6 @@ def deserialize(cls, data: JsonDict) -> 'FuncDef':
         ret.arg_names = data['arg_names']
         ret.arg_kinds = [ArgKind(x) for x in data['arg_kinds']]
         # Leave these uninitialized so that future uses will trigger an error
-        del ret.arguments
         del ret.max_pos
         del ret.min_args
         return ret
diff --git a/mypy/types.py b/mypy/types.py
index f0f7add2d92f..dc78fdbdd931 100644
--- a/mypy/types.py
+++ b/mypy/types.py
@@ -1524,16 +1524,13 @@ def __init__(self,
             # after serialization, but it is useful in error messages.
             # TODO: decide how to add more info here (file, line, column)
             # without changing interface hash.
-            self.def_extras = {
-                'first_arg': (
-                    definition.arguments[0].variable.name
-                    if (getattr(definition, 'arguments', None)
-                        and definition.arg_names
-                        and definition.info
-                        and not definition.is_static)
-                    else None
-                ),
-            }
+            first_arg: Optional[str] = None
+            if definition.info and not definition.is_static:
+                if definition.arguments:
+                    first_arg = definition.arguments[0].variable.name
+                elif definition.arg_names:
+                    first_arg = definition.arg_names[0]
+            self.def_extras = {'first_arg': first_arg}
         else:
             self.def_extras = {}
         self.type_guard = type_guard
diff --git a/mypyc/irbuild/mapper.py b/mypyc/irbuild/mapper.py
index 576eacc141df..9c59104fd7ce 100644
--- a/mypyc/irbuild/mapper.py
+++ b/mypyc/irbuild/mapper.py
@@ -142,10 +142,10 @@ def fdef_to_sig(self, fdef: FuncDef) -> FuncSignature:
         # the sole way that FuncDecl arguments are tracked. This is
         # generally fine except in some cases (like for computing
         # init_sig) we need to produce FuncSignatures from a
-        # deserialized FuncDef that lacks arguments. We won't ever
-        # need to use those inside of a FuncIR, so we just make up
-        # some crap.
-        if hasattr(fdef, 'arguments'):
+        # deserialized FuncDef where arguments is the empty list. We
+        # won't ever need to use those inside of a FuncIR, so we just
+        # make up some crap.
+        if fdef.arguments:
             arg_names = [arg.variable.name for arg in fdef.arguments]
         else:
             arg_names = [name or '' for name in fdef.arg_names]
diff --git a/test-data/unit/check-modules.test b/test-data/unit/check-modules.test
index 67767a9114e1..fc9ddedecc69 100644
--- a/test-data/unit/check-modules.test
+++ b/test-data/unit/check-modules.test
@@ -3190,3 +3190,35 @@ from dir1 import *
 from .test2 import *
 [file dir1/test2.py]
 from test1 import aaaa  # E: Module "test1" has no attribute "aaaa"
+
+[case testIncompatibleOverrideFromCachedModuleIncremental]
+import b
+[file a.py]
+class Foo:
+    def frobnicate(self, *args, **kwargs): pass
+[file b.py]
+from a import Foo
+class Bar(Foo):
+    def frobnicate(self) -> None: pass
+[file b.py.2]
+from a import Foo
+class Bar(Foo):
+    def frobnicate(self, *args) -> None: pass
+[file b.py.3]
+from a import Foo
+class Bar(Foo):
+    def frobnicate(self, *args) -> None: pass # type: ignore[override] # I know
+[builtins fixtures/tuple.pyi]
+[builtins fixtures/dict.pyi]
+[out1]
+tmp/b.py:3: error: Signature of "frobnicate" incompatible with supertype "Foo"
+tmp/b.py:3: note:      Superclass:
+tmp/b.py:3: note:          def frobnicate(self, *args: Any, **kwargs: Any) -> Any
+tmp/b.py:3: note:      Subclass:
+tmp/b.py:3: note:          def frobnicate(self) -> None
+[out2]
+tmp/b.py:3: error: Signature of "frobnicate" incompatible with supertype "Foo"
+tmp/b.py:3: note:      Superclass:
+tmp/b.py:3: note:          def frobnicate(self, *args: Any, **kwargs: Any) -> Any
+tmp/b.py:3: note:      Subclass:
+tmp/b.py:3: note:          def frobnicate(self, *args: Any) -> None