diff --git a/.circleci/config.yml b/.circleci/config.yml
new file mode 100644
index 00000000..ca429902
--- /dev/null
+++ b/.circleci/config.yml
@@ -0,0 +1,74 @@
+version: 2
+
+jobs:
+  build:
+    working_directory: ~/work
+    docker:
+      - image: circleci/python:latest
+
+    steps:
+      - checkout
+      - run: .circleci/launch-job aarch64
+      - run: .circleci/launch-job arm
+      - run: .circleci/launch-job i686
+      - run: .circleci/launch-job x86_64
+
+  # aarch64-linux-android-4.9
+  aarch64:
+    working_directory: ~/work
+    docker:
+      - image: toktoknet/ghc-android:latest.aarch64
+
+    steps:
+      - checkout
+      - restore_cache:
+          key: v1-cabal-cache-aarch64
+      - run: android/build.sh
+      - save_cache:
+          key: v1-cabal-cache-aarch64
+          paths: [~/.ghc/android-21/aarch64-linux-android-4.9]
+
+  # arm-linux-androideabi-4.9
+  arm:
+    working_directory: ~/work
+    docker:
+      - image: toktoknet/ghc-android:latest.arm
+
+    steps:
+      - checkout
+      - restore_cache:
+          key: v1-cabal-cache-arm
+      - run: android/build.sh
+      - save_cache:
+          key: v1-cabal-cache-arm
+          paths: [~/.ghc/android-9/arm-linux-androideabi-4.9]
+
+  # x86-4.9
+  i686:
+    working_directory: ~/work
+    docker:
+      - image: toktoknet/ghc-android:latest.i686
+
+    steps:
+      - checkout
+      - restore_cache:
+          key: v1-cabal-cache-i686
+      - run: android/build.sh
+      - save_cache:
+          key: v1-cabal-cache-i686
+          paths: [~/.ghc/android-9/x86-4.9]
+
+  # x86_64-4.9
+  x86_64:
+    working_directory: ~/work
+    docker:
+      - image: toktoknet/ghc-android:latest.x86_64
+
+    steps:
+      - checkout
+      - restore_cache:
+          key: v1-cabal-cache-x86_64
+      - run: android/build.sh
+      - save_cache:
+          key: v1-cabal-cache-x86_64
+          paths: [~/.ghc/android-21/x86_64-4.9]
diff --git a/.circleci/launch-job b/.circleci/launch-job
new file mode 100755
index 00000000..eafbdbf1
--- /dev/null
+++ b/.circleci/launch-job
@@ -0,0 +1,6 @@
+#!/bin/sh
+
+curl --user ${CIRCLE_API_TOKEN}: \
+  --data build_parameters[CIRCLE_JOB]=$1 \
+  --data revision=$CIRCLE_SHA1 \
+  https://circleci.com/api/v1.1/project/github/$CIRCLE_PROJECT_USERNAME/$CIRCLE_PROJECT_REPONAME/tree/$CIRCLE_BRANCH
diff --git a/.travis/android-install b/.travis/android-install
deleted file mode 100755
index 0de7ed6a..00000000
--- a/.travis/android-install
+++ /dev/null
@@ -1,5 +0,0 @@
-#!/bin/sh
-
-docker pull $DOCKER_IMAGE
-docker run --rm $DOCKER_IMAGE cat /root/dockrun > dockrun
-chmod +x dockrun
diff --git a/.travis/android-script b/.travis/android-script
deleted file mode 100755
index 0e980d01..00000000
--- a/.travis/android-script
+++ /dev/null
@@ -1,4 +0,0 @@
-#!/bin/sh
-
-./dockrun target-cabal configure -flibrary-only
-./dockrun target-cabal build
diff --git a/android/build.sh b/android/build.sh
new file mode 100755
index 00000000..9bf7b063
--- /dev/null
+++ b/android/build.sh
@@ -0,0 +1,20 @@
+#!/bin/bash
+
+set -exu
+
+export SCRIPT_DIR="$( cd "$( dirname "${BASH_SOURCE[0]}" )" && pwd )"
+
+$NDK_TARGET-cabal update
+
+$SCRIPT_DIR/user-scripts/cabal-install-clock.sh
+$SCRIPT_DIR/user-scripts/cabal-install-network.sh
+$SCRIPT_DIR/user-scripts/cabal-install-setup.sh distributive 0.5.0.2
+$SCRIPT_DIR/user-scripts/cabal-install-setup.sh comonad 5
+$SCRIPT_DIR/user-scripts/cabal-install-setup.sh entropy 0.3.7
+$SCRIPT_DIR/user-scripts/cabal-install-zlib.sh
+$SCRIPT_DIR/user-scripts/install-happy.sh
+$SCRIPT_DIR/user-scripts/install-hspec.sh
+$SCRIPT_DIR/user-scripts/install-libsodium.sh
+
+$NDK_TARGET-cabal install --enable-tests --enable-benchmarks --only-dependencies
+$NDK_TARGET-cabal install -flibrary-only
diff --git a/android/patches/hs-clock-ffi.patch b/android/patches/hs-clock-ffi.patch
new file mode 100644
index 00000000..b74e5127
--- /dev/null
+++ b/android/patches/hs-clock-ffi.patch
@@ -0,0 +1,21 @@
+diff -u -r a/System/Clock.hsc b/System/Clock.hsc
+--- a/System/Clock.hsc  2016-04-20 02:14:45.000000000 +0100
++++ b/System/Clock.hsc  2017-06-09 12:15:31.229226983 +0100
+@@ -41,8 +41,6 @@
+ #  endif
+ #endif
+
+-#let alignment t = "%lu", (unsigned long)offsetof(struct {char x__; t (y__); }, y__)
+-
+ -- | Clock types. A clock may be system-wide (that is, visible to all processes)
+ --   or per-process (measuring time that is meaningful only within a process).
+ --   All implementations shall support CLOCK_REALTIME. (The only suspend-aware
+@@ -216,7 +214,7 @@
+ #else
+ instance Storable TimeSpec where
+   sizeOf _ = #{size struct timespec}
+-  alignment _ = #{alignment struct timespec}
++  alignment _ = #{const __alignof__(struct timespec)}
+   poke ptr ts = do
+       let xs :: #{type time_t} = fromIntegral $ sec ts
+           xn :: #{type long} = fromIntegral $ nsec ts
diff --git a/android/patches/hs-network-ffi.patch b/android/patches/hs-network-ffi.patch
new file mode 100644
index 00000000..d9ac4cc9
--- /dev/null
+++ b/android/patches/hs-network-ffi.patch
@@ -0,0 +1,12 @@
+diff -u -r a/Network/Socket/Types.hsc b/Network/Socket/Types.hsc
+--- a/Network/Socket/Types.hsc	2017-05-30 20:10:33.000000000 +0000
++++ b/Network/Socket/Types.hsc	2017-06-10 16:34:51.782365107 +0000
+@@ -1085,7 +1085,7 @@
+ 
+ instance Storable In6Addr where
+     sizeOf _    = #const sizeof(struct in6_addr)
+-    alignment _ = #alignment struct in6_addr
++    alignment _ = #const __alignof__(struct in6_addr)
+ 
+     peek p = do
+         a <- peek32 p 0
diff --git a/android/patches/hs-zlib-ffi.patch b/android/patches/hs-zlib-ffi.patch
new file mode 100644
index 00000000..4b4ad19f
--- /dev/null
+++ b/android/patches/hs-zlib-ffi.patch
@@ -0,0 +1,67 @@
+diff -ru a/Codec/Compression/Zlib/Stream.hsc b/Codec/Compression/Zlib/Stream.hsc
+--- a/Codec/Compression/Zlib/Stream.hsc	2015-05-16 15:12:10.000000000 +0200
++++ b/Codec/Compression/Zlib/Stream.hsc	2016-07-04 22:25:40.933314724 +0200
+@@ -2,6 +2,9 @@
+ #if __GLASGOW_HASKELL__ >= 702
+ {-# LANGUAGE DeriveGeneric #-}
+ #endif
++#if __GLASGOW_HASKELL__ >= 706
++{-# LANGUAGE CApiFFI #-}
++#endif
+ -----------------------------------------------------------------------------
+ -- |
+ -- Copyright   :  (c) 2006-2015 Duncan Coutts
+@@ -1007,7 +1010,19 @@
+ --
+ -- So we define c_inflateInit2 and c_deflateInit2 here as wrappers around
+ -- their _ counterparts and pass the extra args.
+-
++--
++-- As of GHC 7.6, we can import macros directly using the CApiFFI extension.
++-- This avoids the need for the hsc2hs #{const_str} construct, which means
++-- hsc2hs can run in cross-compilation mode.
++
++#if __GLASGOW_HASKELL__ >= 706
++foreign import capi unsafe "zlib.h inflateInit2"
++  c_inflateInit2 :: StreamState -> CInt -> IO CInt
++
++foreign import capi unsafe "zlib.h deflateInit2"
++  c_deflateInit2 :: StreamState
++                 -> CInt -> CInt -> CInt -> CInt -> CInt -> IO CInt
++#else
+ foreign import ccall unsafe "zlib.h inflateInit2_"
+   c_inflateInit2_ :: StreamState -> CInt -> Ptr CChar -> CInt -> IO CInt
+ 
+@@ -1016,15 +1031,6 @@
+   withCAString #{const_str ZLIB_VERSION} $ \versionStr ->
+     c_inflateInit2_ z n versionStr (#{const sizeof(z_stream)} :: CInt)
+ 
+-foreign import ccall unsafe "zlib.h inflate"
+-  c_inflate :: StreamState -> CInt -> IO CInt
+-
+-foreign import ccall unsafe "zlib.h &inflateEnd"
+-  c_inflateEnd :: FinalizerPtr StreamState
+-
+-foreign import ccall unsafe "zlib.h inflateReset"
+-  c_inflateReset :: StreamState -> IO CInt
+-
+ foreign import ccall unsafe "zlib.h deflateInit2_"
+   c_deflateInit2_ :: StreamState
+                   -> CInt -> CInt -> CInt -> CInt -> CInt
+@@ -1036,6 +1042,16 @@
+ c_deflateInit2 z a b c d e =
+   withCAString #{const_str ZLIB_VERSION} $ \versionStr ->
+     c_deflateInit2_ z a b c d e versionStr (#{const sizeof(z_stream)} :: CInt)
++#endif
++
++foreign import ccall unsafe "zlib.h inflate"
++  c_inflate :: StreamState -> CInt -> IO CInt
++
++foreign import ccall unsafe "zlib.h &inflateEnd"
++  c_inflateEnd :: FinalizerPtr StreamState
++
++foreign import ccall unsafe "zlib.h inflateReset"
++  c_inflateReset :: StreamState -> IO CInt
+ 
+ foreign import ccall unsafe "zlib.h deflateSetDictionary"
+   c_deflateSetDictionary :: StreamState
diff --git a/android/user-scripts/cabal-install-clock.sh b/android/user-scripts/cabal-install-clock.sh
new file mode 100755
index 00000000..cf0b87b6
--- /dev/null
+++ b/android/user-scripts/cabal-install-clock.sh
@@ -0,0 +1,21 @@
+#!/bin/bash
+
+export THIS_DIR="$( cd "$( dirname "${BASH_SOURCE[0]}" )" && pwd )"
+source $HOME/ghc-build/set-env.sh
+set -x
+####################################################################################################
+
+CLOCK_PACKAGE=$NDK/cabal/packages/hackage.haskell.org/clock/0.7.2/clock-0.7.2.tar.gz
+
+if [ -f "$CLOCK_PACKAGE" ]; then
+  exit 0
+fi
+
+$NDK_TARGET-cabal fetch clock-0.7.2
+tar zxf $CLOCK_PACKAGE
+pushd clock-0.7.2
+patch -p1 < $SCRIPT_DIR/patches/hs-clock-ffi.patch
+$NDK_TARGET-cabal install
+popd
+
+rm -rf clock*
diff --git a/android/user-scripts/cabal-install-network.sh b/android/user-scripts/cabal-install-network.sh
new file mode 100755
index 00000000..f544e52c
--- /dev/null
+++ b/android/user-scripts/cabal-install-network.sh
@@ -0,0 +1,21 @@
+#!/bin/bash
+
+export THIS_DIR="$( cd "$( dirname "${BASH_SOURCE[0]}" )" && pwd )"
+source $HOME/ghc-build/set-env.sh
+set -x
+####################################################################################################
+
+NETWORK_PACKAGE=$NDK/cabal/packages/hackage.haskell.org/network/2.6.3.2/network-2.6.3.2.tar.gz
+
+if [ -f "$NETWORK_PACKAGE" ]; then
+  exit 0
+fi
+
+$NDK_TARGET-cabal fetch network-2.6.3.2
+tar zxf $NETWORK_PACKAGE
+pushd network-2.6.3.2
+patch -p1 < $SCRIPT_DIR/patches/hs-network-ffi.patch
+$NDK_TARGET-cabal install
+popd
+
+rm -rf network*
diff --git a/android/user-scripts/cabal-install-setup.sh b/android/user-scripts/cabal-install-setup.sh
new file mode 100755
index 00000000..34fc7b2a
--- /dev/null
+++ b/android/user-scripts/cabal-install-setup.sh
@@ -0,0 +1,22 @@
+#!/bin/bash
+
+export THIS_DIR="$( cd "$( dirname "${BASH_SOURCE[0]}" )" && pwd )"
+source $HOME/ghc-build/set-env.sh
+set -x
+####################################################################################################
+
+PACKAGE=$NDK/cabal/packages/hackage.haskell.org/$1/$2/$1-$2.tar.gz
+
+if [ -f "$PACKAGE" ]; then
+  exit 0
+fi
+
+$NDK_TARGET-cabal fetch $1-$2
+tar zxf $PACKAGE
+
+pushd $1-$2
+$HOME/.ghc/android-host/bin/cabal configure || true
+$NDK_TARGET-cabal install
+popd
+
+rm -rf $1*
diff --git a/android/user-scripts/cabal-install-zlib.sh b/android/user-scripts/cabal-install-zlib.sh
new file mode 100755
index 00000000..4a504907
--- /dev/null
+++ b/android/user-scripts/cabal-install-zlib.sh
@@ -0,0 +1,21 @@
+#!/bin/bash
+
+export THIS_DIR="$( cd "$( dirname "${BASH_SOURCE[0]}" )" && pwd )"
+source $HOME/ghc-build/set-env.sh
+set -x
+####################################################################################################
+
+ZLIB_PACKAGE=$NDK/cabal/packages/hackage.haskell.org/zlib/0.6.1.1/zlib-0.6.1.1.tar.gz
+
+if [ -f "$ZLIB_PACKAGE" ]; then
+  exit 0
+fi
+
+$NDK_TARGET-cabal fetch zlib-0.6.1.1
+tar zxf $ZLIB_PACKAGE
+pushd zlib-0.6.1.1
+patch -p1 < $SCRIPT_DIR/patches/hs-zlib-ffi.patch
+$NDK_TARGET-cabal install
+popd
+
+rm -rf zlib*
diff --git a/android/user-scripts/install-happy.sh b/android/user-scripts/install-happy.sh
new file mode 100755
index 00000000..cdbb113f
--- /dev/null
+++ b/android/user-scripts/install-happy.sh
@@ -0,0 +1,32 @@
+#!/bin/bash
+
+export THIS_DIR="$( cd "$( dirname "${BASH_SOURCE[0]}" )" && pwd )"
+source $HOME/ghc-build/set-env.sh
+set -x
+####################################################################################################
+
+if [ -f "$PLATFORM_PREFIX/.cabal/bin/happy" ]; then
+  exit 0
+fi
+
+#
+# Terminology:
+#   build platform: The system platform we're building on. Build platform
+#     executables can be executed during build.
+#   host platform: The system platform we're building *for*. Host executables
+#     can run on the device we're building for, but can't run during build.
+#
+# We first install happy for the build platform, then for the host platform, and
+# then we overwrite the host platform's happy with the build platform's happy.
+#
+# We do this because otherwise packages depending on happy will try to build a
+# host happy and run it during build.
+#
+# We also use cabal-install-setup.sh to build happy for the host platform,
+# because it uses a non-simple setup, so we need to first build the setup
+# program for the build platform.
+#
+
+cabal install happy
+$THIS_DIR/cabal-install-setup.sh happy 1.19.5
+cp $HOME/.cabal/bin/happy $PLATFORM_PREFIX/.cabal/bin/
diff --git a/android/user-scripts/install-hspec.sh b/android/user-scripts/install-hspec.sh
new file mode 100755
index 00000000..1e6ce4e4
--- /dev/null
+++ b/android/user-scripts/install-hspec.sh
@@ -0,0 +1,16 @@
+#!/bin/bash
+
+export THIS_DIR="$( cd "$( dirname "${BASH_SOURCE[0]}" )" && pwd )"
+source $HOME/ghc-build/set-env.sh
+set -x
+####################################################################################################
+
+if [ -f "$PLATFORM_PREFIX/.cabal/bin/hspec-discover" ]; then
+  exit 0
+fi
+
+# See install-happy.sh for explanation for why we do this.
+
+cabal install hspec-discover
+$THIS_DIR/cabal-install-setup.sh hspec-discover 2.4.3
+cp $HOME/.cabal/bin/hspec-discover $PLATFORM_PREFIX/.cabal/bin/
diff --git a/android/user-scripts/install-libsodium.sh b/android/user-scripts/install-libsodium.sh
new file mode 100755
index 00000000..99c8fa09
--- /dev/null
+++ b/android/user-scripts/install-libsodium.sh
@@ -0,0 +1,20 @@
+#!/bin/bash
+
+source $HOME/ghc-build/set-env.sh
+####################################################################################################
+
+if [ -f "$NDK_ADDON_PREFIX/lib/libsodium.a" ]; then
+  exit 0
+fi
+
+cd $NDK_ADDON_SRC
+apt-get source libsodium
+
+pushd libsodium*
+autoreconf -i
+./configure --prefix="$NDK_ADDON_PREFIX" --host=$NDK_TARGET --build=$BUILD_ARCH --with-build-cc=$BUILD_GCC --enable-static --disable-shared
+make $MAKEFLAGS
+make install
+popd
+
+rm -rf libsodium*
diff --git a/hstox.cabal b/hstox.cabal
index 35e4e79b..7aaba7f0 100644
--- a/hstox.cabal
+++ b/hstox.cabal
@@ -43,9 +43,7 @@ library
     , lens-family
     , MonadRandom
     , mtl
-    -- network-2.6.2.1 is the last version that can be cross-compiled, so we install
-    -- it explicitly here.
-    , network                   <= 2.6.2.1
+    , network
     , network-msgpack-rpc       >= 0.0.3
     , saltine
     , random
diff --git a/src/tox/Network/Tox/TimedT.hs b/src/tox/Network/Tox/TimedT.hs
index 6d2c6c95..ffa5501c 100644
--- a/src/tox/Network/Tox/TimedT.hs
+++ b/src/tox/Network/Tox/TimedT.hs
@@ -23,7 +23,7 @@ newtype TimedT m a = TimedT (ReaderT Timestamp m a)
   deriving (Monad, Applicative, Functor, MonadState s, MonadWriter w
     , MonadRandomBytes, MonadTrans, MonadIO, Networked, Keyed)
 
-runTimedT :: Monad m => TimedT m a -> Timestamp -> m a
+runTimedT :: TimedT m a -> Timestamp -> m a
 runTimedT (TimedT m) = runReaderT m
 
 instance Monad m => Timed (TimedT m) where