diff --git a/GnosisSafe.sol b/GnosisSafe.sol
index f09408754..fe1c396cf 100644
--- a/GnosisSafe.sol
+++ b/GnosisSafe.sol
@@ -286,7 +286,7 @@ contract GnosisSafe {
         view
         returns (bytes32)
     {
-        return keccak256(byte(0x19), this, to, value, data, operation, _nonce);
+        return keccak256(byte(0x19), byte(0), this, to, value, data, operation, _nonce);
     }
 
     /// @dev Returns array of owners.