diff --git a/tox.ini b/tox.ini
index f3a7ba4ea0..6acff6b8e8 100644
--- a/tox.ini
+++ b/tox.ini
@@ -647,6 +647,8 @@ deps =
     spark-v3.1: pyspark~=3.1.0
     spark-v3.3: pyspark~=3.3.0
     spark-v3.5: pyspark~=3.5.0
+    # TODO: update to ~=4.0.0 once stable is out
+    spark-v4.0: pyspark==4.0.0.dev2
     spark-latest: pyspark
 
     # Starlette