diff --git a/bitcoin/src/blockdata/witness.rs b/bitcoin/src/blockdata/witness.rs
index d8fa1fa17..20efc0b5f 100644
--- a/bitcoin/src/blockdata/witness.rs
+++ b/bitcoin/src/blockdata/witness.rs
@@ -397,19 +397,24 @@ mod test {
         let control_block = hex!("02");
         // annex starting with 0x50 causes the branching logic.
         let annex = hex!("50");
+        let signature = vec![0xff; 64];
 
         let witness_vec = vec![tapscript.clone(), control_block.clone()];
-        let witness_vec_annex = vec![tapscript.clone(), control_block.clone(), annex];
+        let witness_vec_annex = vec![tapscript.clone(), control_block.clone(), annex.clone()];
+        let witness_vec_key_spend_annex = vec![signature, annex];
 
         let witness_serialized: Vec<u8> = serialize(&witness_vec);
         let witness_serialized_annex: Vec<u8> = serialize(&witness_vec_annex);
+        let witness_serialized_key_spend_annex: Vec<u8> = serialize(&witness_vec_key_spend_annex);
 
         let witness = deserialize::<Witness>(&witness_serialized[..]).unwrap();
         let witness_annex = deserialize::<Witness>(&witness_serialized_annex[..]).unwrap();
+        let witness_key_spend_annex = deserialize::<Witness>(&witness_serialized_key_spend_annex[..]).unwrap();
 
         // With or without annex, the tapscript should be returned.
         assert_eq!(witness.taproot_control_block(), Some(&control_block[..]));
         assert_eq!(witness_annex.taproot_control_block(), Some(&control_block[..]));
+        assert!(witness_key_spend_annex.taproot_control_block().is_none())
     }
 
     #[test]