diff --git a/deltachat-ffi/deltachat.h b/deltachat-ffi/deltachat.h
index 93db76c14..4e8b307d8 100644
--- a/deltachat-ffi/deltachat.h
+++ b/deltachat-ffi/deltachat.h
@@ -1587,7 +1587,7 @@ int             dc_set_chat_profile_image    (dc_context_t* context, uint32_t ch
  *
  * @memberof dc_context_t
  * @param chat_id The chat ID to set the mute duration.
- * @param duration The duration (0 for no mute, 1 for forever mute, >1 unix timestamp it until it should be unmuted again)
+ * @param duration The duration (0 for no mute, -1 for forever mute, >0 unix timestamp it until it should be unmuted again)
  * @param context The context as created by dc_context_new().
  * @return 1=success, 0=error
  */
@@ -2936,7 +2936,7 @@ int             dc_chat_is_sending_locations (const dc_chat_t* chat);
 
 
 /**
- * Check wether the chat is currently muted
+ * Check whether the chat is currently muted
  *
  * @memberof dc_chat_t
  * @param chat The chat object.
@@ -2950,7 +2950,7 @@ int             dc_chat_is_muted (const dc_chat_t* chat);
  *
  * @memberof dc_chat_t
  * @param chat The chat object.
- * @return 0=not muted, 1=muted, (x>1)=unix timestamp until mute is lifted
+ * @return 0=not muted, -1=forever muted, (x>0)=unix timestamp until mute is lifted
  */
 int64_t          dc_chat_get_mute_duration (const dc_chat_t* chat);
 
diff --git a/src/chat.rs b/src/chat.rs
index 82796d55d..0d1c9533a 100644
--- a/src/chat.rs
+++ b/src/chat.rs
@@ -980,7 +980,7 @@ pub struct ChatInfo {
     ///       simple `has_draft` bool instead.
     pub draft: String,
 
-    /// Wether the chat is muted
+    /// Whether the chat is muted
     ///
     /// The exact time its muted can be found out via the `chat.mute_duration` property
     pub is_muted: bool,
@@ -1929,7 +1929,7 @@ impl MuteDuration {
     pub fn serialize(&self) -> i64 {
         match &self {
             MuteDuration::NotMuted => 0,
-            MuteDuration::Forever => 1,
+            MuteDuration::Forever => -1,
             MuteDuration::MutedUntilTimestamp(timestamp) => *timestamp as i64, // TODO make this pretier?
         }
     }
@@ -1937,7 +1937,7 @@ impl MuteDuration {
     pub fn deserialize(value: i64) -> MuteDuration {
         match value {
             0 => MuteDuration::NotMuted,
-            1 => MuteDuration::Forever,
+            -1 => MuteDuration::Forever,
             _ => MuteDuration::MutedUntilTimestamp(value),
         }
     }