diff --git a/src/transform/src/dataflow.rs b/src/transform/src/dataflow.rs
index e8fc4d8b2a5f7..d11954c2baf73 100644
--- a/src/transform/src/dataflow.rs
+++ b/src/transform/src/dataflow.rs
@@ -90,6 +90,11 @@ pub fn optimize_dataflow(
             transform_ctx,
         )?;
 
+        assert!(
+            dataflow.objects_to_build.len() <= 2,
+            "there should be at most two objects to build"
+        );
+
         optimize_dataflow_monotonic(dataflow, transform_ctx)?;
     }