diff --git a/.travis.yml b/.travis.yml
index 6de1cb1..03c14d8 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -18,12 +18,12 @@ install:
 # Install `cargo-deadlinks` unless it is currently installed.
 - command -v cargo-deadlinks &> /dev/null || cargo install cargo-deadlinks
 # Install nightly toolchain.
-- rustup toolchain install $(NIGHTLY_TOOLCHAIN)
+- rustup toolchain install $NIGHTLY_TOOLCHAIN
 script:
 - export CC=/usr/bin/gcc-6
 - export CXX=/usr/bin/g++-6
 # Make sure fuzz targets are not broken.
-- rustup run $(NIGHTLY_TOOLCHAIN) cargo check --tests --manifest-path=fuzz/Cargo.toml
+- rustup run $NIGHTLY_TOOLCHAIN cargo check --tests --manifest-path=fuzz/Cargo.toml
 - ./test.sh
 - ./doc.sh
 after_success: |
diff --git a/doc.sh b/doc.sh
index e86fcef..4c20b7a 100755
--- a/doc.sh
+++ b/doc.sh
@@ -4,7 +4,7 @@ set -eux
 
 cd $(dirname $0)
 
-rustup run $(NIGHTLY_TOOLCHAIN) cargo doc
+rustup run $NIGHTLY_TOOLCHAIN cargo doc
 
 # cargo-deadlinks will check any links in docs generated by `cargo doc`.
 # This is useful as rustdoc uses raw links which are error prone.