diff --git a/.coveragerc b/.coveragerc
index 2515d6b90..c56196726 100644
--- a/.coveragerc
+++ b/.coveragerc
@@ -1,5 +1,6 @@
 [run]
 branch = True
+source = dulwich
 
 [report]
 exclude_lines =
diff --git a/.travis.yml b/.travis.yml
index 8a798655b..302eeec48 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -27,11 +27,11 @@ install:
 
 script:
   # Test without c extensions
-  - python -m coverage run -p --source=dulwich -m unittest dulwich.tests.test_suite
+  - python -m coverage run -p -m unittest dulwich.tests.test_suite
 
   # Test with c extensions
   - python setup.py build_ext -i
-  - python -m coverage run -p --source=dulwich -m unittest dulwich.tests.test_suite
+  - python -m coverage run -p -m unittest dulwich.tests.test_suite
 
   # Style
   - make style
diff --git a/Makefile b/Makefile
index 706ab0acb..8054ee2c4 100644
--- a/Makefile
+++ b/Makefile
@@ -65,7 +65,7 @@ before-push: check
 	git diff origin/master | $(PEP8) --diff
 
 coverage:
-	$(COVERAGE) run --source=dulwich -m unittest dulwich.tests.test_suite dulwich.contrib.test_suite
+	$(COVERAGE) run -m unittest dulwich.tests.test_suite dulwich.contrib.test_suite
 
 coverage-html: coverage
 	$(COVERAGE) html