diff --git a/pyproject.toml b/pyproject.toml
index 2c3fd74cd..d3c2f327a 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -49,7 +49,7 @@ jupyter = [
     "mistune!=3.1.0",  # there is a bug in it
 ]
 zarr = [
-    "zarr>=2.16.0",
+    "zarr>=2.16.0,<3.0.0a0", # not yet compatible with 3.0.*
 ]
 fcs = [
     "readfcs>=1.1.9",