diff --git a/gastest/Main.hs b/gastest/Main.hs
new file mode 100644
index 000000000..20d9d6459
--- /dev/null
+++ b/gastest/Main.hs
@@ -0,0 +1,39 @@
+{-# LANGUAGE LambdaCase #-}
+
+module Main where
+
+import Prelude hiding (Word)
+
+import Control.Lens (view)
+import Control.Monad (forM_, replicateM)
+import Control.Monad.IO.Class (liftIO)
+import Control.Monad.Reader (runReaderT)
+import Control.Monad.State (execState)
+import Data.Foldable (maximumBy, minimumBy)
+import Data.Ord (comparing)
+import Data.Text (unpack)
+import EVM (gas, state)
+import Hedgehog.Gen (sample, prune)
+import System.Environment (getArgs)
+
+import Echidna.ABI
+import Echidna.Config
+import Echidna.Exec
+import Echidna.Solidity
+
+
+main :: IO ()
+main = let conf m = runReaderT m defaultConfig in getArgs >>= \case
+  []     -> putStrLn "need to specify solidity file"
+  prog:_ -> do
+    (v,a,_) <- conf $ loadSolidity prog Nothing
+    forM_ a $ \f -> do
+      inputs <- liftIO $ replicateM 1000 . sample . prune . conf $ genAbiCall f
+      let results = map (\i -> (i, g v - g (execState (execCall i) v))) inputs; g = view $ state . gas
+      mapM_ putStrLn [ unpack $ fst f
+                     , pp maximumBy "Max" results, pp minimumBy "Min" results
+                     , "  Avg: " ++ show ( fromIntegral (sum $ snd <$> results)
+                                         / fromIntegral (length results) :: Double)
+                     ] where pp f s r = let (c, n) = f (comparing snd) r in
+                                            "  " ++ s ++ ": " ++ show (toInteger n)
+                                                 ++ " (" ++ displayAbiCall c ++ ")"
diff --git a/lib/Echidna/ABI.hs b/lib/Echidna/ABI.hs
index c8cd16c41..7b85de1bd 100644
--- a/lib/Echidna/ABI.hs
+++ b/lib/Echidna/ABI.hs
@@ -12,6 +12,7 @@ module Echidna.ABI (
   , genAbiBool
   , genAbiBytes
   , genAbiBytesDynamic
+  , genAbiCall
   , genAbiInt
   , genInteractions
   , genAbiString
@@ -32,7 +33,7 @@ import Data.DoubleWord       (Word128(..), Word160(..))
 import Data.Monoid           ((<>))
 import Data.ByteString       (ByteString)
 import Data.Text             (Text, unpack)
-import Data.Vector           (Vector)
+import Data.Vector           (Vector, generateM)
 import Hedgehog.Internal.Gen (MonadGen)
 import GHC.Exts              (IsList(..), Item)
 import Hedgehog.Range        (exponential, exponentialFrom, constant, singleton, Range)
@@ -115,14 +116,16 @@ genAbiType = Gen.choice [ pure AbiBytesDynamicType
                         ]
 
 genVecOfType :: (MonadReader Config m, MonadGen m) => AbiType -> Range Int -> m (Vector AbiValue)
-genVecOfType t r = fmap fromList . Gen.list r $ case t of
-  AbiUIntType    n    -> genAbiUInt n
-  AbiIntType     n    -> genAbiInt n
-  AbiAddressType      -> genAbiAddress
-  AbiBoolType         -> genAbiBool
-  AbiBytesType   n    -> genAbiBytes n
-  AbiArrayType   n t' -> genAbiArray n t'
-  _ -> error "Arrays must only contain statically sized types"
+genVecOfType t r = do
+  s <- Gen.integral r
+  generateM s $ \_ -> case t of
+    AbiUIntType    n    -> genAbiUInt n
+    AbiIntType     n    -> genAbiInt n
+    AbiAddressType      -> genAbiAddress
+    AbiBoolType         -> genAbiBool
+    AbiBytesType   n    -> genAbiBytes n
+    AbiArrayType   n t' -> genAbiArray n t'
+    _ -> error "Arrays must only contain statically sized types"
 
 genAbiArrayDynamic :: (MonadReader Config m, MonadGen m) => AbiType -> m AbiValue
 genAbiArrayDynamic t = AbiArrayDynamic t <$> genVecOfType t (constant 0 256)
diff --git a/package.yaml b/package.yaml
index b07fd00ef..f4e27b9d4 100644
--- a/package.yaml
+++ b/package.yaml
@@ -60,3 +60,7 @@ executables:
     main: Main.hs
     source-dirs: perprop
     dependencies: echidna
+  gastest-exe:
+    main: Main.hs
+    source-dirs: gastest
+    dependencies: echidna