diff --git a/CHANGELOG.md b/CHANGELOG.md
index d7da1d9..3f63d3e 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -10,6 +10,7 @@ Changelog
   console. This makes it clear what's the preferred option.
 * Use Idempotency-Key header to prevent multiple toots being posted if request
   is retried
+* Fix a bug where all media would be marked as sensitive
 
 **0.18.0 (2018-06-12)**
 
diff --git a/toot/api.py b/toot/api.py
index 74dbf95..a86ef25 100644
--- a/toot/api.py
+++ b/toot/api.py
@@ -100,7 +100,7 @@ def post_status(
         'status': status,
         'media_ids[]': media_ids,
         'visibility': visibility,
-        'sensitive': sensitive,
+        'sensitive': "true" if sensitive else "false",
         'spoiler_text': spoiler_text,
         'in_reply_to_id': in_reply_to_id,
     }, headers=headers).json()