diff --git a/src/runtime/communication.rs b/src/runtime/communication.rs
index e7595a26225f9768e0f34f37f5567810c43cd62a..09c99516ea20c2d9fa74789d4b088b30e6b68af6 100644
--- a/src/runtime/communication.rs
+++ b/src/runtime/communication.rs
@@ -100,8 +100,9 @@ impl Controller {
             if branches.contains_key(&predicate) {
                 // TODO what do I do with redundant predicates?
                 unimplemented!(
-                    "Having multiple batches with the same
-                    predicate requires the support of oracle boolean variables"
+                    "Duplicate predicate {:#?}!\nHaving multiple batches with the same
+                    predicate requires the support of oracle boolean variables",
+                    &predicate,
                 )
             }
             let branch = BranchN { to_get: gets, gotten: Default::default(), sync_batch_index };