diff --git a/src/exo/master/placement.py b/src/exo/master/placement.py
index a0604055..5f191b84 100644
--- a/src/exo/master/placement.py
+++ b/src/exo/master/placement.py
@@ -112,7 +112,11 @@ def place_instance(
         cycle for cycle in smallest_cycles if topology.is_rdma_cycle(cycle)
     ]
 
-    if command.instance_meta == InstanceMeta.MlxJaccl and smallest_rdma_cycles != []:
+    if command.instance_meta == InstanceMeta.MlxJaccl:
+        if not smallest_rdma_cycles:
+            raise ValueError(
+                "Requested RDMA (MlxJaccl) but no RDMA-connected cycles available"
+            )
         smallest_cycles = smallest_rdma_cycles
 
     cycles_with_leaf_nodes: list[Cycle] = [