diff --git a/.coveragerc b/.coveragerc
new file mode 100644
index 0000000..c5fad9a
--- /dev/null
+++ b/.coveragerc
@@ -0,0 +1,9 @@
+[run]
+branch = True
+omit =
+  nmigen/test/*
+  */__init__.py
+
+[report]
+exclude_lines =
+	:nocov:
diff --git a/.gitignore b/.gitignore
index 29542a5..02ef482 100644
--- a/.gitignore
+++ b/.gitignore
@@ -2,3 +2,5 @@
 *.egg-info
 *.il
 *.v
+/.coverage
+/htmlcov