diff --git a/crates/matrix-sdk-crypto/src/backups/keys/compat.rs b/crates/matrix-sdk-crypto/src/backups/keys/compat.rs
index e5eb01612..59c32e6ad 100644
--- a/crates/matrix-sdk-crypto/src/backups/keys/compat.rs
+++ b/crates/matrix-sdk-crypto/src/backups/keys/compat.rs
@@ -106,12 +106,12 @@ impl PkDecryption {
 
         let keys = Keys::new(shared_secret);
 
-        let cipher = Aes256CbcDec::new(keys.aes_key(), keys.iv());
-        let decrypted = cipher.decrypt_padded_vec_mut::<Pkcs7>(&message.ciphertext)?;
-
         let hmac = keys.hmac();
         hmac.verify_truncated_left(&message.mac)?;
 
+        let cipher = Aes256CbcDec::new(keys.aes_key(), keys.iv());
+        let decrypted = cipher.decrypt_padded_vec_mut::<Pkcs7>(&message.ciphertext)?;
+
         Ok(decrypted)
     }