diff --git a/chain-impl-mockchain/src/ledger/ledger.rs b/chain-impl-mockchain/src/ledger/ledger.rs
index a5bbe813a..1a8fdd4da 100644
--- a/chain-impl-mockchain/src/ledger/ledger.rs
+++ b/chain-impl-mockchain/src/ledger/ledger.rs
@@ -1878,9 +1878,9 @@ fn match_identifier_witness<'a>(
 fn input_single_account_verify<'a>(
     mut ledger: account::Ledger,
     _block0_hash: &HeaderId,
-    _sign_data_hash: &TransactionSignDataHash,
+    sign_data_hash: &TransactionSignDataHash,
     account: &account::Identifier,
-    _witness: &'a account::Witness,
+    witness: &'a account::Witness,
     spending_counter: account::SpendingCounter,
     value: Value,
 ) -> Result<account::Ledger, Error> {
@@ -1888,6 +1888,18 @@ fn input_single_account_verify<'a>(
     let new_ledger = ledger.remove_value(account, spending_counter, value)?;
     ledger = new_ledger;
 
+    let verified = witness.verify(
+        account.as_ref(),
+        &WitnessAccountData(sign_data_hash.as_ref().to_vec()),
+    );
+
+    if verified == chain_crypto::Verification::Failed {
+        return Err(Error::AccountInvalidSignature {
+            account: account.clone(),
+            witness: Witness::Account(spending_counter, witness.clone()),
+        });
+    };
+
     // TODO verify sig(pub_key,data)
     Ok(ledger)
 }
diff --git a/chain-impl-mockchain/src/transaction/witness.rs b/chain-impl-mockchain/src/transaction/witness.rs
index 31faf5fc1..278a66881 100644
--- a/chain-impl-mockchain/src/transaction/witness.rs
+++ b/chain-impl-mockchain/src/transaction/witness.rs
@@ -99,7 +99,7 @@ impl AsRef<[u8]> for WitnessUtxoData {
     }
 }
 
-pub struct WitnessAccountData(Vec<u8>);
+pub struct WitnessAccountData(pub Vec<u8>);
 
 impl WitnessAccountData {
     pub fn new(