diff --git a/.travis.yml b/.travis.yml
index 69aff29..eb4299c 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -2,10 +2,14 @@ language: python
 python: 2.7
 install:
   - pip install tox
+  - pip install coveralls
 env:
   - TOX_ENV=py26
   - TOX_ENV=py27
   - TOX_ENV=py32
   - TOX_ENV=py33
+  - TOX_ENV=coverage
 script:
-  - tox -e $TOX_ENV
+  - tox
+after_success:
+  - coveralls
diff --git a/requirements.txt b/requirements.txt
index ffe2fce..c9571a9 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -1 +1,3 @@
-six
+# workaround for problematic nose2 requirements
+six>=1.1,<1.4
+
diff --git a/test_requirements.txt b/test_requirements.txt
index 50cb553..cafd3e0 100644
--- a/test_requirements.txt
+++ b/test_requirements.txt
@@ -1,3 +1 @@
-# workaround for problematic nose2 requirements
-six>=1.1,<1.4
 nose2
diff --git a/tox.ini b/tox.ini
index b2c3cfb..ff14e97 100644
--- a/tox.ini
+++ b/tox.ini
@@ -43,3 +43,11 @@ deps =
 deps =
     {[testenv]deps}
     biopython
+
+[testenv:coverage]
+basepython = python2.7
+deps =
+    {[testenv:py27]deps}
+    coverage
+commands =
+    coverage run --branch -m nose2