diff --git a/pyproject.toml b/pyproject.toml
index ed2ef238..a062423f 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -55,6 +55,7 @@ dev = [
     "pre-commit-hooks>=6.0.0",
     "pytest>=8.4.2",
     "pytest-dependency>=0.6.0",
+    "pytest-cov>=7.0.0",
     "typeguard>=4.4.4",
     "xdoctest[colors]>=1.3.0",
     "Pygments>=2.19.2"
@@ -151,8 +152,9 @@ tests = ["tests", "*/tests"]
 
 [tool.coverage.run]
 branch = true
-source = ["src/mdio", "tests"]
+source = ["src/mdio"]
 relative_files = true
+omit = ["tests/*", "noxfile.py"]
 
 [tool.coverage.report]
 show_missing = true