diff --git a/backend/src/api/user.ts b/backend/src/api/user.ts
index 1c611be..7ebec19 100644
--- a/backend/src/api/user.ts
+++ b/backend/src/api/user.ts
@@ -107,8 +107,17 @@ userRouter.get("/queue", async (req: LRequest, res) => {
     const { token, db } = req;
     let user = Object.assign({}, await userFromSession(token, db));
 
+    // We want to add the id of the vocabulary that the metadata belongs to
+    // to the metadata object, so that we can identify the original vocabulary
+    // item later on.
     const sm2 = user.vocabMetadata;
-    const data = Object.keys(sm2).map(id => Object.assign({}, sm2[parseInt(id)], { id, }));
+    const assignId = (id_str: string) => {
+        const id = parseInt(id_str);
+        return Object.assign({}, sm2[id], { id, });
+    };
+    const data = Object.keys(sm2).map(assignId);
+
+    // Sort the vocabulary based on the next due date...
     const sorted = data.sort((a: any, b: any) => {
         if (a.nextDueDate > b.nextDueDate)
             return 1;
@@ -116,7 +125,9 @@ userRouter.get("/queue", async (req: LRequest, res) => {
             return -1;
 
         return 0;
-    }).slice(0, 20)
+    })
+        // ...and return 20 at max.
+        .slice(0, 20)
         .map((el: any) => {
             return parseInt(el.id);
         });