diff --git a/.travis.yml b/.travis.yml
index 937507439f9f9..2b392c798aced 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -14,4 +14,8 @@ matrix:
 script:
   - cargo test --all
   - cargo clean
-  - ./publish-wasm.sh
+  - ./init.sh
+  - ./build.sh
+  - if [ "$TRAVIS_PULL_REQUEST" != "true" ] && [ "$TRAVIS_BRANCH" == "master" ]; then
+      ./publish-wasm.sh;
+    fi
diff --git a/build.sh b/build.sh
index dd47753730759..8cac3c5e5c1af 100755
--- a/build.sh
+++ b/build.sh
@@ -1,13 +1,27 @@
-#!/bin/sh
+#!/bin/bash
 
-# NOTE `cargo install wasm-gc` before running this script.
-# NOTE `cargo install --git https://github.com/pepyakin/wasm-export-table.git`
+# This script assumes that all pre-requisites are installed.
 
 set -e
+
+source `dirname "$0"`/common.sh
+
 export CARGO_INCREMENTAL=0
 
-cd demo/runtime/wasm && ./build.sh && cd ../../..
-cd substrate/executor/wasm && ./build.sh && cd ../../..
-cd substrate/test-runtime/wasm && ./build.sh && cd ../../..
-cd polkadot/runtime/wasm && ./build.sh && cd ../../..
-cd polkadot/parachain/test-chains && ./build.sh && cd ../../..
+# Save current directory.
+pushd .
+
+cd $ROOT
+
+for SRC in "${SRCS[@]}"
+do
+  echo "*** Building wasm binaries in $SRC"
+  cd $SRC
+
+  ./build.sh
+
+  cd - >> /dev/null
+done
+
+# Restore initial directory.
+popd
diff --git a/common.sh b/common.sh
new file mode 100644
index 0000000000000..ba131bd969b5e
--- /dev/null
+++ b/common.sh
@@ -0,0 +1,22 @@
+#!/bin/bash
+
+ROOT=`dirname "$0"`
+
+# A list of directories which contain wasm projects.
+SRCS=(
+	"polkadot/runtime/wasm"
+	"substrate/executor/wasm"
+	"demo/runtime/wasm"
+	"substrate/test-runtime/wasm"
+	"polkadot/parachain/test-chains/basic_add"
+)
+
+# Make pushd/popd silent.
+
+pushd () {
+	command pushd "$@" > /dev/null
+}
+
+popd () {
+	command popd "$@" > /dev/null
+}
diff --git a/demo/runtime/wasm/build.sh b/demo/runtime/wasm/build.sh
index 53ca2a0018ce5..093e8c1a8a21b 100755
--- a/demo/runtime/wasm/build.sh
+++ b/demo/runtime/wasm/build.sh
@@ -1,4 +1,4 @@
-#!/bin/sh
+#!/bin/bash
 set -e
 
 cargo +nightly build --target=wasm32-unknown-unknown --release
diff --git a/demo/runtime/wasm/init.sh b/demo/runtime/wasm/init.sh
deleted file mode 100755
index e8b4387a2f998..0000000000000
--- a/demo/runtime/wasm/init.sh
+++ /dev/null
@@ -1,7 +0,0 @@
-#!/bin/sh
-
-rustup update nightly
-rustup target add wasm32-unknown-unknown --toolchain nightly
-rustup update stable
-cargo install --git https://github.com/alexcrichton/wasm-gc
-cargo install --git https://github.com/pepyakin/wasm-export-table.git
diff --git a/init.sh b/init.sh
new file mode 100755
index 0000000000000..6e70b76d32712
--- /dev/null
+++ b/init.sh
@@ -0,0 +1,19 @@
+#!/bin/bash
+
+set -e
+
+echo "*** Initilising WASM build environment"
+
+rustup update nightly
+rustup target add wasm32-unknown-unknown --toolchain nightly
+rustup update stable
+
+# Install wasm-gc. It's useful for stripping slimming down wasm binaries.
+command -v wasm-gc || \
+	cargo +nightly install --git https://github.com/alexcrichton/wasm-gc
+
+# At the moment of writing, rustc still uses LLD 6 which produces wasm binaries
+# that don't export a table. Meanwhile, we are waiting for LLD 7 to come
+# in rustc we could use this handy little tool.
+command -v wasm-export-table || \
+	cargo +nightly install --git https://github.com/pepyakin/wasm-export-table.git
diff --git a/polkadot/parachain/test-chains/basic_add/build.sh b/polkadot/parachain/test-chains/basic_add/build.sh
new file mode 100755
index 0000000000000..965913f4957ee
--- /dev/null
+++ b/polkadot/parachain/test-chains/basic_add/build.sh
@@ -0,0 +1,12 @@
+#!/bin/bash
+set -e
+
+# Make LLD produce a binary that imports memory from the outside environment.
+export RUSTFLAGS="-C link-arg=--import-memory"
+
+cargo +nightly build --target=wasm32-unknown-unknown --release --no-default-features
+
+for i in basic_add
+do
+	wasm-gc target/wasm32-unknown-unknown/release/$i.wasm target/wasm32-unknown-unknown/release/$i.compact.wasm
+done
diff --git a/polkadot/parachain/test-chains/build.sh b/polkadot/parachain/test-chains/build.sh
index 2b876634e88c7..d46a63561363d 100755
--- a/polkadot/parachain/test-chains/build.sh
+++ b/polkadot/parachain/test-chains/build.sh
@@ -1,4 +1,4 @@
-#!/bin/sh
+#!/bin/bash
 set -e
 
 rm -rf ./target
diff --git a/polkadot/runtime/wasm/build.sh b/polkadot/runtime/wasm/build.sh
index d48d10a062d38..8920ca8bbb35c 100755
--- a/polkadot/runtime/wasm/build.sh
+++ b/polkadot/runtime/wasm/build.sh
@@ -1,4 +1,4 @@
-#!/bin/sh
+#!/bin/bash
 set -e
 
 cargo +nightly build --target=wasm32-unknown-unknown --release
diff --git a/polkadot/runtime/wasm/init.sh b/polkadot/runtime/wasm/init.sh
deleted file mode 100755
index 703207078c511..0000000000000
--- a/polkadot/runtime/wasm/init.sh
+++ /dev/null
@@ -1,7 +0,0 @@
-#!/bin/sh
-
-rustup update nightly
-rustup target add wasm32-unknown-unknown --toolchain nightly
-rustup update stable
-cargo +nightly install --git https://github.com/alexcrichton/wasm-gc
-cargo +nightly install --git https://github.com/pepyakin/wasm-export-table.git
diff --git a/publish-wasm.sh b/publish-wasm.sh
index 2a42504eef6b9..de60ad69c54c9 100755
--- a/publish-wasm.sh
+++ b/publish-wasm.sh
@@ -1,35 +1,26 @@
 #!/bin/bash
 
+# Publish wasm binaries into the special repository.
+# This script assumes that wasm binaries have already been built.
+# Requires GH_TOKEN environment variable to be defined.
+
 set -e
 
+source `dirname "$0"`/common.sh
+
+if [ -z ${GH_TOKEN+x} ]; then
+	echo "GH_TOKEN environment variable is not set"
+	exit 1
+fi
+
 REPO="github.com/paritytech/polkadot-wasm-bin.git"
 REPO_AUTH="${GH_TOKEN}:@${REPO}"
-SRCS=( "polkadot/runtime/wasm" "substrate/executor/wasm" "demo/runtime/wasm" "substrate/test-runtime/wasm" "polkadot/parachain/test-chains" )
 DST=".wasm-binaries"
 TARGET="wasm32-unknown-unknown"
 UTCDATE=`date -u "+%Y%m%d.%H%M%S.0"`
 
 pushd .
 
-echo "*** Initilising WASM build environment"
-cd polkadot/runtime/wasm
-./init.sh || true
-cd ../../..
-
-for SRC in "${SRCS[@]}"
-do
-  echo "*** Building wasm binaries in $SRC"
-  cd $SRC
-  ./build.sh
-  cd ../../..
-done
-
-if [ "$TRAVIS_PULL_REQUEST" != "false" -o "$TRAVIS_BRANCH" != "master" ]; then
-  popd
-  echo "*** Skipping wasm binary publish"
-  exit 0
-fi
-
 echo "*** Cloning repo"
 rm -rf $DST
 git clone https://$REPO $DST
diff --git a/substrate/executor/wasm/build.sh b/substrate/executor/wasm/build.sh
index 83acc2700d37d..7dcb11af109bc 100755
--- a/substrate/executor/wasm/build.sh
+++ b/substrate/executor/wasm/build.sh
@@ -1,4 +1,4 @@
-#!/bin/sh
+#!/bin/bash
 set -e
 
 cargo +nightly build --target=wasm32-unknown-unknown --release
diff --git a/substrate/test-runtime/wasm/build.sh b/substrate/test-runtime/wasm/build.sh
index e2d1faeb7312b..4cb6edb9c9caa 100755
--- a/substrate/test-runtime/wasm/build.sh
+++ b/substrate/test-runtime/wasm/build.sh
@@ -1,4 +1,4 @@
-#!/bin/sh
+#!/bin/bash
 set -e
 
 cargo +nightly build --target=wasm32-unknown-unknown --release
diff --git a/substrate/test-runtime/wasm/init.sh b/substrate/test-runtime/wasm/init.sh
deleted file mode 100755
index e8b4387a2f998..0000000000000
--- a/substrate/test-runtime/wasm/init.sh
+++ /dev/null
@@ -1,7 +0,0 @@
-#!/bin/sh
-
-rustup update nightly
-rustup target add wasm32-unknown-unknown --toolchain nightly
-rustup update stable
-cargo install --git https://github.com/alexcrichton/wasm-gc
-cargo install --git https://github.com/pepyakin/wasm-export-table.git