diff --git a/tests/spec/run.js b/tests/spec/run.js
index 67322c2..bac3627 100644
--- a/tests/spec/run.js
+++ b/tests/spec/run.js
@@ -413,7 +413,13 @@ async function runOperation(op, entities) {
         case 'findOneAndDelete': return unwrapFam(await target.findOneAndDelete(args.filter, options(args)));
 
         // -- collection / index management ----------------------------------
-        case 'createIndex': return await target.createIndex(args.keys, options(args));
+        // `name` is positional for `dropIndex` and an *option* for this one,
+        // so it is put back after `options` strips it -- without that, a
+        // corpus asking for a named index silently gets a derived name.
+        case 'createIndex': return await target.createIndex(args.keys, {
+            ...options(args),
+            ...(args.name !== undefined ? { name: args.name } : {}),
+        });
         case 'dropIndex': return await target.dropIndex(args.name, options(args));
         case 'createCollection': return void (await target.createCollection(args.collection, options(args, ['collection'])));
         case 'dropCollection': return void (await target.dropCollection(args.collection, options(args, ['collection'])));