diff --git a/ci/rustup.sh b/ci/rustup.sh
index 16483d4..b2be2a9 100755
--- a/ci/rustup.sh
+++ b/ci/rustup.sh
@@ -7,6 +7,11 @@ set -ex
 export TRAVIS_RUST_VERSION
 for TRAVIS_RUST_VERSION in 1.8.0 stable beta nightly; do
     run="rustup run $TRAVIS_RUST_VERSION"
+    if [ "$TRAVIS_RUST_VERSION" = 1.8.0 ]; then
+      # libc 0.2.34 started using #[deprecated]
+      $run cargo generate-lockfile
+      $run cargo update --package libc --precise 0.2.33 || :
+    fi
     $run cargo build --verbose
     $run $PWD/ci/test_full.sh
 done
diff --git a/ci/test_full.sh b/ci/test_full.sh
index c64610f..0d1bd85 100755
--- a/ci/test_full.sh
+++ b/ci/test_full.sh
@@ -4,8 +4,14 @@ set -ex
 
 echo Testing num-traits on rustc ${TRAVIS_RUST_VERSION}
 
-# num-integer should build and test everywhere.
+# num-traits should build and test everywhere.
 cargo build --verbose
 cargo test --verbose
 
-# We have no features to test...
+# It should build with minimal features too.
+cargo build --no-default-features
+cargo test --no-default-features
+
+# num-traits with explicit std feature
+cargo build --verbose --no-default-features --features="$feature"
+cargo test --verbose --no-default-features --features="$feature"