diff --git a/.travis.yml b/.travis.yml
index fa73140..7a43c0d 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -19,6 +19,9 @@ matrix:
     # Test serde support on stable, assuming that if it works there it'll work everywhere:
     - rust: stable
       env: TEST_COMMAND=test FEATURE='--features=serde'
+    # Test with the optional sha2 feature enabled:
+    - rust: stable
+      env: TEST_COMMAND=test FEATURE='--features=sha2'
 
 script:
   - cargo $TEST_COMMAND $FEATURES