diff --git a/.travis.yml b/.travis.yml
index 29c8df2f..e7e3f78f 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -26,6 +26,7 @@ install:
  - unset CC
  - export PATH=$HOME/.local/bin:$PATH
  - ./.travis/install-libsecp256k1.sh
+ - ./.travis/install-libff.sh
  - ./.travis/install-ghr.sh
  - ./.travis/install-stack.sh
  - ./.travis/install-solc.sh
diff --git a/.travis/install-libff.sh b/.travis/install-libff.sh
new file mode 100755
index 00000000..55c81c1d
--- /dev/null
+++ b/.travis/install-libff.sh
@@ -0,0 +1,23 @@
+#!/bin/sh
+
+set -eux
+
+if ls /usr/local/lib | grep -q libff; then exit 0; fi
+
+git clone https://github.com/scipr-lab/libff --recursive
+git submodule init && git submodule update
+cd libff
+ARGS="-DWITH_PROCPS=OFF"
+CXXFLAGS=""
+if [ "$TRAVIS_OS_NAME" = "osx" ]; then
+  export LDFLAGS=-L/usr/local/opt/openssl/lib
+  export CPPFLAGS=-I/usr/local/opt/openssl/include
+  export CXXFLAGS=-I/usr/local/opt/openssl/include
+  ARGS="$ARGS -DOPENSSL_INCLUDE_DIR=/usr/local/opt/openssl/include/openssl -DCURVE=ALT_BN128"
+  sed -i '' 's/STATIC/SHARED/' libff/CMakeLists.txt # Fix GHC segfaults from hell (idk why)
+  sed -i '' 's/STATIC/SHARED/' depends/CMakeLists.txt
+fi
+mkdir build
+cd build
+CXXFLAGS="-fPIC $CXXFLAGS" cmake $ARGS ..
+make && sudo make install
diff --git a/examples/solidity/exercises/testme.sol b/examples/solidity/exercises/testme.sol
index b5e73153..d165f24c 100644
--- a/examples/solidity/exercises/testme.sol
+++ b/examples/solidity/exercises/testme.sol
@@ -21,6 +21,7 @@ contract Canal {
       }
     }
   }
+
   function raise(bool first_gate) {
     if(first_gate) {
       first_gate_up = true;
@@ -28,4 +29,14 @@ contract Canal {
       second_gate_up = true;
     }
   }
+
+  function echidna_bothdown() returns (bool) {
+    return(first_gate_up || second_gate_up);
+  }
+
+  function echidna_can_lower_second() returns (bool) {
+    bool a0 = lower(true);
+    raise(true);
+    return(a0);
+  }
 }
diff --git a/lib/Echidna/Exec.hs b/lib/Echidna/Exec.hs
index 0a3e0351..3c57ba83 100644
--- a/lib/Echidna/Exec.hs
+++ b/lib/Echidna/Exec.hs
@@ -69,8 +69,10 @@ execTxWith h m t = do og <- get
                       case (res, isRight $ t ^. call) of
                         (Reversion,   _)         -> put og
                         (VMFailure x, _)         -> h x
-                        (VMSuccess bc, True) -> hasLens %= execState ( replaceCodeOfSelf bc
-                                                                        >> loadContract (t ^. dst))
+                        (VMSuccess bc, True)     -> (hasLens %=) . execState $ do
+                          env . contracts . at (t ^. dst) . _Just . contractcode .= InitCode ""
+                          replaceCodeOfSelf (RuntimeCode bc) 
+                          loadContract (t ^. dst)
                         _                        -> pure ()
                       return res
 
diff --git a/lib/Echidna/Solidity.hs b/lib/Echidna/Solidity.hs
index fcadb030..cb08fc12 100644
--- a/lib/Echidna/Solidity.hs
+++ b/lib/Echidna/Solidity.hs
@@ -100,7 +100,7 @@ contracts fp = do
 populateAddresses :: [Addr] -> Integer -> VM -> VM
 populateAddresses []     _ vm = vm
 populateAddresses (a:as) b vm = populateAddresses as b (vm & set (env . EVM.contracts . at a) (Just account))
-  where account = initialContract mempty & set nonce 1 & set balance (w256 $ fromInteger b)
+  where account = initialContract (RuntimeCode mempty) & set nonce 1 & set balance (w256 $ fromInteger b)
 
 -- | Given an optional contract name and a list of 'SolcContract's, try to load the specified
 -- contract, or, if not provided, the first contract in the list, into a 'VM' usable for Echidna
diff --git a/lib/Echidna/Transaction.hs b/lib/Echidna/Transaction.hs
index bffd7edf..bd8ec933 100644
--- a/lib/Echidna/Transaction.hs
+++ b/lib/Echidna/Transaction.hs
@@ -116,9 +116,9 @@ liftSH = S.state . runState . zoom hasLens
 setupTx :: (MonadState x m, Has VM x) => Tx -> m ()
 setupTx (Tx c s r v) = S.state . runState . zoom hasLens . sequence_ $
   [ result .= Nothing, state . pc .= 0, state . stack .= mempty, state . memory .= mempty, state . gas .= 0xffffffff
-  , env . origin .= s, state . caller .= s, state . callvalue .= v, setup] where
+  , tx . origin .= s, state . caller .= s, state . callvalue .= v, setup] where
     setup = case c of
       Left cd  -> loadContract r >> state . calldata .= encode cd
-      Right bc -> assign (env . contracts . at r) (Just $ initialContract bc) >> loadContract r
+      Right bc -> assign (env . contracts . at r) (Just $ initialContract (RuntimeCode bc)) >> loadContract r
     encode (n, vs) = abiCalldata
       (n <> "(" <> T.intercalate "," (abiTypeSolidity . abiValueType <$> vs) <> ")") $ V.fromList vs
diff --git a/stack.yaml b/stack.yaml
index 3e20e72f..3e1320f1 100644
--- a/stack.yaml
+++ b/stack.yaml
@@ -1,22 +1,27 @@
-resolver: lts-12.18
+resolver: lts-12.10
 
 packages:
 - '.'
 
 extra-deps:
+- git: https://github.com/dapphub/dapptools.git
+  commit: 80c39ced5653727e7e38873bb215a99bc6acc56c
+  subdirs:
+  - src/hevm
+
 - ghci-pretty-0.0.2
-- hevm-0.24
-- HSH-2.1.3
-- ipprint-0.6
 - multiset-0.3.4.1
-- readline-1.0.3.0
 - restless-git-0.7
 - rosezipper-0.2
 - s-cargot-0.1.4.0
-- sr-extra-1.46.3.2
 - text-format-0.3.2
 - tree-view-0.5
+- HSH-2.1.3
+- ipprint-0.6
+- sr-extra-1.46.3.2
 - Unixutils-1.54.1
+- github: dmjio/semver-range
+  commit: d8d9db892ddb6ae267c9bcbc4f6602668433f12a
 
 extra-include-dirs:
 - /usr/local/opt/readline/include