diff --git a/pyproject.toml b/pyproject.toml
index b20075fe..dcaafd00 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -66,7 +66,7 @@ ignore = ["W503", "E203", "E501", "D202"]
 per-file-ignores = ["tests/*:F811,F401,F403"]
 
 [tool.coverage.run]
-source = "bellows"
+source = ["bellows"]
 omit = [
     "bellows/cli/*.py",
     "bellows/typing.py",