diff --git a/api_docs/outgoing-webhooks.md b/api_docs/outgoing-webhooks.md
index e676d0696d..7413bc3644 100644
--- a/api_docs/outgoing-webhooks.md
+++ b/api_docs/outgoing-webhooks.md
@@ -149,6 +149,10 @@ Here's how we fill in the fields that a Slack-format webhook expects:
         <tr>
             <td><code>text</code></td>
             <td>The content of the message (in Markdown)</td>
+        </tr>
+         <tr>
+            <td><code>command</code></td>
+            <td>The bot mention</td>
         </tr>
         <tr>
             <td><code>trigger_word</code></td>
@@ -173,8 +177,8 @@ The above data is posted as list of tuples (not JSON), here's an example:
  ('timestamp', 1532078950),
  ('user_id', 'U21'),
  ('user_name', 'Full Name'),
- ('command', '@**test**'),
- ('text', 'The content of the message'),
+ ('command', '/test'),
+ ('text', 'content'),
  ('trigger_word', 'mention'),
  ('service_id', 27)]
 ```
diff --git a/zerver/lib/outgoing_webhook.py b/zerver/lib/outgoing_webhook.py
index 0123f2e32d..df74c08052 100644
--- a/zerver/lib/outgoing_webhook.py
+++ b/zerver/lib/outgoing_webhook.py
@@ -137,7 +137,7 @@ class SlackOutgoingWebhookService(OutgoingWebhookServiceInterface):
         command_re = r"(@\*\*[\w]+\*\*)"
         text = event["command"]
         message_parts = re.split(command_re, text)
-        if re.fullmatch(command_re, message_parts[1]):
+        if len(message_parts) == 3 and re.fullmatch(command_re, message_parts[1]):
             slash_command = "/" + message_parts[1][3:-2]
             text = message_parts[2].strip()