diff --git a/zerver/data_import/slack.py b/zerver/data_import/slack.py
index e5855676fc..efa2d5008e 100644
--- a/zerver/data_import/slack.py
+++ b/zerver/data_import/slack.py
@@ -1318,7 +1318,7 @@ def fetch_team_icons(
     records = []
 
     team_icons_dict = team_info_dict["icon"]
-    if "image_default" in team_icons_dict and team_icons_dict["image_default"]:
+    if team_icons_dict.get("image_default", False):
         return []
 
     icon_url = (
diff --git a/zerver/lib/markdown/api_arguments_table_generator.py b/zerver/lib/markdown/api_arguments_table_generator.py
index 9d30106346..d528dcf2e8 100644
--- a/zerver/lib/markdown/api_arguments_table_generator.py
+++ b/zerver/lib/markdown/api_arguments_table_generator.py
@@ -259,6 +259,6 @@ def generate_data_type(schema: Mapping[str, Any]) -> str:
         data_type = "(" + generate_data_type(schema["items"]) + ")[]"
     else:
         data_type = schema["type"]
-        if "nullable" in schema and schema["nullable"]:
+        if schema.get("nullable", False):
             data_type = data_type + " | null"
     return data_type
diff --git a/zerver/lib/outgoing_webhook.py b/zerver/lib/outgoing_webhook.py
index ff6ac8c668..b45decb172 100644
--- a/zerver/lib/outgoing_webhook.py
+++ b/zerver/lib/outgoing_webhook.py
@@ -81,7 +81,7 @@ class GenericOutgoingWebhookService(OutgoingWebhookServiceInterface):
 
     @override
     def process_success(self, response_json: Dict[str, Any]) -> Optional[Dict[str, Any]]:
-        if "response_not_required" in response_json and response_json["response_not_required"]:
+        if response_json.get("response_not_required", False):
             return None
 
         if "response_string" in response_json:
diff --git a/zerver/webhooks/slack_incoming/view.py b/zerver/webhooks/slack_incoming/view.py
index 9d8d09e11b..238abf5f74 100644
--- a/zerver/webhooks/slack_incoming/view.py
+++ b/zerver/webhooks/slack_incoming/view.py
@@ -61,16 +61,16 @@ def api_slack_incoming_webhook(
         user_specified_topic = "(no topic)"
 
     pieces: List[str] = []
-    if "blocks" in payload and payload["blocks"]:
+    if payload.get("blocks"):
         pieces += map(render_block, payload["blocks"])
 
-    if "attachments" in payload and payload["attachments"]:
+    if payload.get("attachments"):
         pieces += map(render_attachment, payload["attachments"])
 
     body = "\n\n".join(piece.strip() for piece in pieces if piece.strip() != "")
 
-    if body == "" and "text" in payload and payload["text"]:
-        if "icon_emoji" in payload and payload["icon_emoji"]:
+    if body == "" and payload.get("text"):
+        if payload.get("icon_emoji"):
             body = payload["icon_emoji"].tame(check_string) + " "
         body += payload["text"].tame(check_string)
         body = body.strip()
@@ -192,16 +192,16 @@ def render_attachment(attachment: WildValue) -> str:
     # rest of the fields we handle here are legacy fields. These fields are
     # optional and may contain null values.
     pieces = []
-    if "title" in attachment and attachment["title"]:
+    if attachment.get("title"):
         title = attachment["title"].tame(check_string)
-        if "title_link" in attachment and attachment["title_link"]:
+        if attachment.get("title_link"):
             title_link = attachment["title_link"].tame(check_url)
             pieces.append(f"## [{title}]({title_link})")
         else:
             pieces.append(f"## {title}")
-    if "pretext" in attachment and attachment["pretext"]:
+    if attachment.get("pretext"):
         pieces.append(attachment["pretext"].tame(check_string))
-    if "text" in attachment and attachment["text"]:
+    if attachment.get("text"):
         pieces.append(attachment["text"].tame(check_string))
     if "fields" in attachment:
         fields = []
@@ -210,20 +210,20 @@ def render_attachment(attachment: WildValue) -> str:
                 title = field["title"].tame(check_string)
                 value = field["value"].tame(check_string)
                 fields.append(f"*{title}*: {value}")
-            elif "title" in field and field["title"]:
+            elif field.get("title"):
                 title = field["title"].tame(check_string)
                 fields.append(f"*{title}*")
-            elif "value" in field and field["value"]:
+            elif field.get("value"):
                 value = field["value"].tame(check_string)
                 fields.append(f"{value}")
         pieces.append("\n".join(fields))
-    if "blocks" in attachment and attachment["blocks"]:
+    if attachment.get("blocks"):
         pieces += map(render_block, attachment["blocks"])
-    if "image_url" in attachment and attachment["image_url"]:
+    if attachment.get("image_url"):
         pieces.append("[]({})".format(attachment["image_url"].tame(check_url)))
-    if "footer" in attachment and attachment["footer"]:
+    if attachment.get("footer"):
         pieces.append(attachment["footer"].tame(check_string))
-    if "ts" in attachment and attachment["ts"]:
+    if attachment.get("ts"):
         time = attachment["ts"].tame(check_int)
         pieces.append(f"<time:{time}>")