diff --git a/src/mouse.rs b/src/mouse.rs
index 8b5c1b0..ee106c6 100644
--- a/src/mouse.rs
+++ b/src/mouse.rs
@@ -71,7 +71,7 @@ impl Action {
             v.extend((1..=11).map(Action::Button));
         }
         if types.contains(&SPECIAL) {
-            v.extend((1..SPECIALS.len() as u32 - 1).map(|n| Action::Special(SPECIAL_BASE + n)));
+            v.extend((1..SPECIALS.len() as u32).map(|n| Action::Special(SPECIAL_BASE + n)));
         }
         if types.contains(&NONE) {
             v.push(Action::None);
@@ -349,3 +349,16 @@ impl HidppDpi {
         Ok(u16::from_be_bytes([r[4], r[5]]))
     }
 }
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn special_choices_cover_every_entry() {
+        let choices = Action::choices(&[SPECIAL]);
+        // index 0 ("Unknown") stays out, the last entry ("Battery level") is offered
+        assert!(!choices.contains(&Action::Special(SPECIAL_BASE)));
+        assert!(choices.contains(&Action::Special(SPECIAL_BASE + SPECIALS.len() as u32 - 1)));
+    }
+}