diff --git a/pdg/src/info.rs b/pdg/src/info.rs
index cfe5646de8..7fe0fd2745 100644
--- a/pdg/src/info.rs
+++ b/pdg/src/info.rs
@@ -224,10 +224,10 @@ mod test {
 
     fn check_unique(pdg: &Graphs, unique: &[NodeId], non_unique: &[NodeId]) {
         for &unique in unique {
-            assert!(info(pdg, unique).unique);
+            assert!(info(pdg, unique).unique, "expected {unique} to be unique in {pdg}");
         }
         for &non_unique in non_unique {
-            assert!(!info(pdg, non_unique).unique);
+            assert!(!info(pdg, non_unique).unique, "expected {non_unique} to be non-unique in {pdg}");
         }
     }