diff --git a/pyproject.toml b/pyproject.toml
index d687f883cc4b4bb9c2b1dd1701b79876d4aa3d77..6b499afbe9dc803d95909788e00032698b759854 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -50,10 +50,14 @@ secondary = true
 python = "^3.9"
 aleksis-core = "^2.7"
 aleksis-app-chronos = "^2.2"
+aleksis-app-stoelindeling = { version = "^1.0", optional = true }
 
 [tool.poetry.dev-dependencies]
 aleksis-builddeps = "*"
 
+[tool.poetry.extras]
+seatingplans = ["aleksis-app-stoelindeling"]
+
 [tool.poetry.plugins."aleksis.app"]
 alsijil = "aleksis.apps.alsijil.apps:AlsijilConfig"