diff --git a/.travis.yml b/.travis.yml
index 7041ae8d65..06857f4fb7 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -7,6 +7,8 @@ jobs:
   allow_failures:
     - rust: nightly
   fast_finish: true
+env:
+  - RUST_TEST_THREADS=1
 before_script:
   - rustup component add rustfmt
 script: