diff --git a/river/stats/kolmogorov_smirnov.py b/river/stats/kolmogorov_smirnov.py
index afacd14e7f..d3f0432b23 100644
--- a/river/stats/kolmogorov_smirnov.py
+++ b/river/stats/kolmogorov_smirnov.py
@@ -277,8 +277,10 @@ def get(self):
 
         if self.statistic == "ks":
             return max(self.treap.max_value, -self.treap.min_value) / self.n_samples
-        else:
+        elif self.statistic == "kuiper":
             return max(self.treap.max_value - self.treap.min_value) / self.n_samples
+        else:
+            raise ValueError(f"Unknown statistic {self.statistic}, expected one of: ks, kuiper")
 
     def test_ks_threshold(self, ca):
         """