diff --git a/Libraries/LibWeb/IndexedDB/Internal/Algorithms.cpp b/Libraries/LibWeb/IndexedDB/Internal/Algorithms.cpp
index 4037204a7e5..045fad8d10e 100644
--- a/Libraries/LibWeb/IndexedDB/Internal/Algorithms.cpp
+++ b/Libraries/LibWeb/IndexedDB/Internal/Algorithms.cpp
@@ -1412,13 +1412,29 @@ WebIDL::ExceptionOr<GC::Ptr<Key>> store_a_record_into_an_object_store(JS::Realm&
             }
         }
 
-        // FIXME: 5. If index’s multiEntry flag is false, or if index key is not an array key
+        // 5. If index’s multiEntry flag is false, or if index key is not an array key
         //    then store a record in index containing index key as its key and key as its value.
         //    The record is stored in index’s list of records such that the list is sorted primarily on the records keys,
         //    and secondarily on the records values, in ascending order.
+        if (!index_multi_entry || !index_key_is_array) {
+            IndexRecord index_record = {
+                .key = *index_key,
+                .value = *key,
+            };
+            index->store_a_record(index_record);
+        }
 
-        // // FIXME: 6. If index’s multiEntry flag is true and index key is an array key,
+        // 6. If index’s multiEntry flag is true and index key is an array key,
         //    then for each subkey of the subkeys of index key store a record in index containing subkey as its key and key as its value.
+        if (index_multi_entry && index_key_is_array) {
+            for (auto const& subkey : index_key->subkeys()) {
+                IndexRecord index_record = {
+                    .key = *subkey,
+                    .value = *key,
+                };
+                index->store_a_record(index_record);
+            }
+        }
     }
 
     // 6. Return key.
diff --git a/Libraries/LibWeb/IndexedDB/Internal/Index.cpp b/Libraries/LibWeb/IndexedDB/Internal/Index.cpp
index ebd280b08d0..70cde9ea2aa 100644
--- a/Libraries/LibWeb/IndexedDB/Internal/Index.cpp
+++ b/Libraries/LibWeb/IndexedDB/Internal/Index.cpp
@@ -4,6 +4,7 @@
  * SPDX-License-Identifier: BSD-2-Clause
  */
 
+#include <AK/QuickSort.h>
 #include <LibWeb/IndexedDB/Internal/Index.h>
 #include <LibWeb/IndexedDB/Internal/ObjectStore.h>
 
@@ -107,4 +108,18 @@ u64 Index::count_records_in_range(GC::Ref<IDBKeyRange> range)
     return count;
 }
 
+void Index::store_a_record(IndexRecord const& record)
+{
+    m_records.append(record);
+
+    // NOTE: The record is stored in index’s list of records such that the list is sorted primarily on the records keys, and secondarily on the records values, in ascending order.
+    AK::quick_sort(m_records, [](auto const& a, auto const& b) {
+        auto key_comparison = Key::compare_two_keys(a.key, b.key);
+        if (key_comparison != 0)
+            return key_comparison < 0;
+
+        return Key::compare_two_keys(a.value, b.value) < 0;
+    });
+}
+
 }
diff --git a/Libraries/LibWeb/IndexedDB/Internal/Index.h b/Libraries/LibWeb/IndexedDB/Internal/Index.h
index 730c4ad2ba0..b8632a70c45 100644
--- a/Libraries/LibWeb/IndexedDB/Internal/Index.h
+++ b/Libraries/LibWeb/IndexedDB/Internal/Index.h
@@ -44,6 +44,7 @@ public:
     Optional<IndexRecord&> first_in_range(GC::Ref<IDBKeyRange> range);
     GC::ConservativeVector<IndexRecord> first_n_in_range(GC::Ref<IDBKeyRange> range, Optional<WebIDL::UnsignedLong> count);
     u64 count_records_in_range(GC::Ref<IDBKeyRange> range);
+    void store_a_record(IndexRecord const& record);
 
     HTML::SerializationRecord referenced_value(IndexRecord const& index_record) const;