diff --git a/pyproject.toml b/pyproject.toml
index 8c88a90de4..14be9d2741 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -116,7 +116,6 @@ ignore = [
     "ANN101", # Missing type annotation for `self` in method
     "ANN102", # Missing type annotation for `cls` in classmethod
     "ANN401", # Dynamically typed expressions (typing.Any) are disallowed
-    "B006", # Do not use mutable data structures for argument defaults
     "B007", # Loop control variable not used within the loop body
     "B008", # Do not perform function calls in argument defaults.
     "B023", # Function definition does not bind loop variable
diff --git a/zerver/lib/test_classes.py b/zerver/lib/test_classes.py
index d85fc4f4ca..d708edf5d5 100644
--- a/zerver/lib/test_classes.py
+++ b/zerver/lib/test_classes.py
@@ -462,7 +462,7 @@ Output:
     def client_post(
         self,
         url: str,
-        info: Union[str, bytes, Dict[str, Any]] = {},
+        info: Union[str, bytes, Mapping[str, Any]] = {},
         skip_user_agent: bool = False,
         follow: bool = False,
         secure: bool = False,
@@ -875,7 +875,7 @@ Output:
         self,
         identifier: str,
         url: str,
-        info: Union[str, bytes, Dict[str, Any]] = {},
+        info: Union[str, bytes, Mapping[str, Any]] = {},
         **extra: str,
     ) -> "TestHttpResponse":
         extra["HTTP_AUTHORIZATION"] = self.encode_uuid(identifier)
@@ -907,7 +907,7 @@ Output:
         self,
         user: UserProfile,
         url: str,
-        info: Union[str, bytes, Dict[str, Any]] = {},
+        info: Union[str, bytes, Mapping[str, Any]] = {},
         intentionally_undocumented: bool = False,
         **extra: str,
     ) -> "TestHttpResponse":