diff --git a/.gitignore b/.gitignore
index f721dfe0751f..9919ac1f0d1a 100644
--- a/.gitignore
+++ b/.gitignore
@@ -160,6 +160,9 @@ testing/talos/talos/tests/devtools/damp.manifest.develop
 tps.log
 tps_result.json
 
+# Unit test
+.pytest_cache/
+
 # Ignore files created when running a reftest.
 lextab.py
 
diff --git a/.hgignore b/.hgignore
index 8ae84ca3a3e2..e9958123af6b 100644
--- a/.hgignore
+++ b/.hgignore
@@ -184,6 +184,9 @@ _OPT\.OBJ/
 # Ignore toolchains.json created by tooltool.
 ^toolchains\.json
 
+# Unit test
+\.pytest_cache/
+
 # Ignore files created when running a reftest.
 ^lextab.py$