diff --git a/lib/Echidna/Solidity.hs b/lib/Echidna/Solidity.hs
index 5e2f327cd..9ef256d91 100644
--- a/lib/Echidna/Solidity.hs
+++ b/lib/Echidna/Solidity.hs
@@ -36,7 +36,7 @@ import Echidna.ABI                (encodeSig, hashSig, stripBytecodeMetadata, fa
 import Echidna.Exec               (execTx)
 import Echidna.RPC                (loadEthenoBatch)
 import Echidna.Types.Signature    (FunctionHash, SolSignature, SignatureMap)
-import Echidna.Types.Tx           (TxConf, TxCall(..), Tx(..))
+import Echidna.Types.Tx           (TxConf, TxCall(..), Tx(..), initialTimestamp, initialBlockNumber)
 import Echidna.Types.World        (World(..))
 import Echidna.Processor
 
@@ -162,7 +162,7 @@ loadLibraries :: (MonadIO m, MonadThrow m, MonadReader x m, Has SolConf x)
               => [SolcContract] -> Addr -> Addr -> VM -> m VM
 loadLibraries []     _  _ vm = return vm
 loadLibraries (l:ls) la d vm = loadLibraries ls (la + 1) d =<< loadRest
-  where loadRest = execStateT (execTx $ Tx (SolCreate $ l ^. creationCode) d la 8000030 0 0 (0,0)) vm
+  where loadRest = execStateT (execTx $ Tx (SolCreate $ l ^. creationCode) d la 8000030 0 0 (initialTimestamp, initialBlockNumber)) vm
 
 -- | Generate a string to use as argument in solc to link libraries starting from addrLibrary
 linkLibraries :: [String] -> String
@@ -234,7 +234,7 @@ loadSpecified name cs = do
     Just (t,_) -> throwM $ TestArgsFound t                      -- Test args check
     Nothing    -> do
       vm <- loadLibraries ls addrLibrary d blank
-      let transaction = unless (isJust fp) $ void . execTx $ Tx (SolCreate bc) d ca 8000030 0 (w256 $ fromInteger balc) (0, 0)
+      let transaction = unless (isJust fp) $ void . execTx $ Tx (SolCreate bc) d ca 8000030 0 (w256 $ fromInteger balc) (initialTimestamp,initialBlockNumber)
       vm' <- execStateT transaction vm
       case currentContract vm' of
         Just _  -> return (vm', neFuns, fst <$> tests, abiMapping)
diff --git a/lib/Echidna/Transaction.hs b/lib/Echidna/Transaction.hs
index 49ea95333..34ec88e43 100644
--- a/lib/Echidna/Transaction.hs
+++ b/lib/Echidna/Transaction.hs
@@ -65,8 +65,10 @@ genTxWith m s r c g gp mv t = do
       v' = genValue ps mv
       rs = NE.fromList . catMaybes $ mkR <$> toList m
       mkR = _2 (flip M.lookup mm . view (bytecode . to stripBytecodeMetadata))
+  (tt,tn) <- t
+  let t' = return (initialTimestamp + tt, initialBlockNumber + tn)
   v'' <- v' <$> s' <*> r' <*> c'
-  Tx <$> (SolCall <$> c') <*> s' <*> (fst <$> r') <*> g <*> gp <*> v'' <*> t
+  Tx <$> (SolCall <$> c') <*> s' <*> (fst <$> r') <*> g <*> gp <*> v'' <*> t'
 
 getSignatures :: MonadRandom m => SignatureMap -> Maybe SignatureMap -> m SignatureMap
 getSignatures hmm Nothing = return hmm
diff --git a/lib/Echidna/Types/Tx.hs b/lib/Echidna/Types/Tx.hs
index ddf9b8967..2f5f8fafe 100644
--- a/lib/Echidna/Types/Tx.hs
+++ b/lib/Echidna/Types/Tx.hs
@@ -23,6 +23,12 @@ data TxCall = SolCreate   ByteString
 makePrisms ''TxCall
 $(deriveJSON defaultOptions ''TxCall)
 
+initialTimestamp :: Word
+initialTimestamp = 1524785992 -- Thu Apr 26 23:39:52 UTC 2018
+
+initialBlockNumber :: Word
+initialBlockNumber = 4370000  -- Initial byzantium block
+
 -- | A transaction is either a @CREATE@ or a regular call with an origin, destination, and value.
 -- Note: I currently don't model nonces or signatures here.
 data Tx = Tx { _call  :: TxCall       -- | Call