diff --git a/core/dr-catalog/src/runner.rs b/core/dr-catalog/src/runner.rs
index b47f850..d0d171f 100644
--- a/core/dr-catalog/src/runner.rs
+++ b/core/dr-catalog/src/runner.rs
@@ -853,11 +853,16 @@ mod tests {
             let seen = seen.clone();
             threads.push(std::thread::spawn(move || {
                 let conn = open(&path);
-                Runner::new(&conn)
+                // Bound to a local rather than left as the block's tail: the
+                // `Runner` borrows `conn`, and a tail expression's temporaries
+                // are dropped *after* the block's locals, so the borrow would
+                // outlive what it borrows.
+                let completed = Runner::new(&conn)
                     .with(recording(vec![JobKind::Thumbnail], seen))
                     .drain_all(0)
                     .unwrap()
-                    .completed
+                    .completed;
+                completed
             }));
         }