diff --git a/.travis.yml b/.travis.yml
index 3cf1344..45feba6 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -25,7 +25,9 @@ script:
 # Make sure fuzz targets are not broken.
 - if [ "$TRAVIS_RUST_VERSION" == "nightly" ]; then cargo check --tests --manifest-path=fuzz/Cargo.toml; fi
 - if [ "$TRAVIS_RUST_VERSION" == "nightly" ]; then cargo check --benches --manifest-path=benches/Cargo.toml; fi
-- ./test.sh
+# Run tests in the release mode since some of the tests from the spec
+# perfrom reaaally bad in the debug mode.
+- CARGOFLAGS=--release ./test.sh
 - ./doc.sh
 after_success: |
   # Build documentation and deploy it to github pages.
diff --git a/test.sh b/test.sh
index 3cef9ad..89da0a1 100755
--- a/test.sh
+++ b/test.sh
@@ -1,9 +1,9 @@
 #!/usr/bin/env bash
 
-set -eux
+set -ex
 
 cd $(dirname $0)
 
-time cargo test
+time cargo test $CARGOFLAGS
 
 cd -