diff --git a/pyproject.toml b/pyproject.toml
index 5c7e60c..bef36b7 100755
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -31,6 +31,10 @@ classifiers = []
 
 [project.optional-dependencies]
 opensimplex = ["opensimplex"]
+test = [
+     "pytest",
+     "opensimplex"
+]
 
 [project.urls]
 Homepage = "https://topotoolbox.github.io"