diff --git a/scripts/run_inference.py b/scripts/run_inference.py
index 3fb6466..4bbc010 100755
--- a/scripts/run_inference.py
+++ b/scripts/run_inference.py
@@ -141,7 +141,7 @@ def main(conf: HydraConfig) -> None:
             sampler.binderlen,
             chain_idx=sampler.chain_idx,
             bfacts=bfacts,
-            idx_pdb=sampler.idx_pdb
+            **({"idx_pdb": sampler.idx_pdb} if hasattr(sampler, "idx_pdb") else {})
         )
 
         # run metadata