diff --git a/.travis.yml b/.travis.yml
index 84fd3f7d..094274b0 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -31,3 +31,5 @@ cache:
     directories:
         - $HOME/.cache/pip
         - $HOME/.cache/pre-commit
+        - $HOME/.rustup
+        - $HOME/.swift
diff --git a/testing/get-swift.sh b/testing/get-swift.sh
index a45291e2..54a37e58 100755
--- a/testing/get-swift.sh
+++ b/testing/get-swift.sh
@@ -4,13 +4,23 @@ set -ex
 
 . /etc/lsb-release
 if [ "$DISTRIB_CODENAME" = "trusty" ]; then
-    SWIFT_URL='https://swift.org/builds/swift-4.0.3-release/ubuntu1404/swift-4.0.3-RELEASE/swift-4.0.3-RELEASE-ubuntu14.04.tar.gz'
+    SWIFT_TARBALL="swift-4.0.3-RELEASE-ubuntu14.04.tar.gz"
+    SWIFT_HASH="dddb40ec4956e4f6a3f4532d859691d5d1ba8822f6e8b4ec6c452172dbede5ae"
+    SWIFT_URL="https://swift.org/builds/swift-4.0.3-release/ubuntu1404/swift-4.0.3-RELEASE/$SWIFT_TARBALL"
 else
-    SWIFT_URL='https://swift.org/builds/swift-4.0.3-release/ubuntu1604/swift-4.0.3-RELEASE/swift-4.0.3-RELEASE-ubuntu16.04.tar.gz'
+    SWIFT_TARBALL="swift-4.0.3-RELEASE-ubuntu16.04.tar.gz"
+    SWIFT_HASH="9adf64cabc7c02ea2d08f150b449b05e46bd42d6e542bf742b3674f5c37f0dbf"
+    SWIFT_URL="https://swift.org/builds/swift-4.0.3-release/ubuntu1604/swift-4.0.3-RELEASE/$SWIFT_TARBALL"
 fi
 
+mkdir -p "$HOME"/.swift
+pushd "$HOME"/.swift
+    wget -N -c "$SWIFT_URL"
+    echo "$SWIFT_HASH  $SWIFT_TARBALL" > hash.txt
+    shasum -a 256 -c hash.txt
+popd
+
 mkdir -p /tmp/swift
 pushd /tmp/swift
-    wget "$SWIFT_URL" -O swift.tar.gz
-    tar -xf swift.tar.gz --strip 1
+    tar -xf "$HOME"/.swift/"$SWIFT_TARBALL" --strip 1
 popd