diff --git a/tox.ini b/tox.ini
index 90ca38e6..5d21e700 100644
--- a/tox.ini
+++ b/tox.ini
@@ -8,7 +8,7 @@ isolated_build = True
 deps=pytest
 extras=diagrams
 commands=
-    pytest tests
+    pytest tests {posargs}
 whitelist_externals=
     pytest
     python