diff --git a/app/Item.php b/app/Item.php
index 5692c4783..60361409e 100644
--- a/app/Item.php
+++ b/app/Item.php
@@ -779,8 +779,9 @@ public function getImageUrlAttribute()
         return sprintf('%s%s', config('app.url'), $this->getImagePath());
     }
 
-    public function syncMatchedAuthorities(\Illuminate\Support\Collection $idsWithPivotData)
+    public function syncMatchedAuthorities(\Illuminate\Support\Collection|array $idsWithPivotData)
     {
+        $idsWithPivotData = collect($idsWithPivotData);
         // Detach automatically-matched authorities that no longer match
         $this->authorities()
             ->wherePivot('automatically_matched', true)
diff --git a/tests/Models/ItemTest.php b/tests/Models/ItemTest.php
index 6fdea5a51..b129d0569 100644
--- a/tests/Models/ItemTest.php
+++ b/tests/Models/ItemTest.php
@@ -187,43 +187,75 @@ protected function createFreeItem()
         ]);
     }
 
-    public function testSyncMatchedAuthorities()
+    public function testSyncMatchedAuthoritiesUpdatesExisting()
     {
-        $authorities = Authority::factory()
-            ->count(5)
+        $item = Item::factory()->create();
+        [$authority1, $authority2] = Authority::factory()
+            ->count(2)
             ->create();
+        $item->authorities()->sync([
+            $authority1->id => ['role' => 'author', 'automatically_matched' => true],
+            $authority2->id => ['role' => 'author', 'automatically_matched' => false],
+        ]);
+
+        $item->syncMatchedAuthorities([
+            $authority1->id => ['role' => 'new-role-1'],
+            $authority2->id => ['role' => 'new-role-2'],
+        ]);
+
+        $this->assertDatabaseHas('authority_item', [
+            'authority_id' => $authority1->id,
+            'item_id' => $item->id,
+            'role' => 'new-role-1',
+            'automatically_matched' => true,
+        ]);
+        $this->assertDatabaseHas('authority_item', [
+            'authority_id' => $authority2->id,
+            'item_id' => $item->id,
+            'role' => 'new-role-2',
+            'automatically_matched' => false,
+        ]);
+    }
+
+    public function testSyncMatchedAuthoritiesDeletesOnlyAutomaticallyMatched()
+    {
         $item = Item::factory()->create();
+        [$authority1, $authority2] = Authority::factory()
+            ->count(2)
+            ->create();
         $item->authorities()->sync([
-            // present in matched authorities
-            $authorities[0]->id => ['role' => 'author', 'automatically_matched' => true],
-            $authorities[1]->id => ['role' => 'author', 'automatically_matched' => false],
-            // missing from matched authorities
-            $authorities[2]->id => ['role' => 'author', 'automatically_matched' => true],
-            $authorities[3]->id => ['role' => 'author', 'automatically_matched' => false],
-        ]);
-
-        $item->syncMatchedAuthorities(
-            collect([
-                $authorities[0]->id => ['role' => 'after'],
-                $authorities[1]->id => ['role' => 'after'],
-                $authorities[4]->id => ['role' => 'after'],
-            ])
-        );
+            $authority1->id => ['automatically_matched' => true, 'role' => 'author'],
+            $authority2->id => ['automatically_matched' => false, 'role' => 'author'],
+        ]);
 
-        $item->refresh();
-        $this->assertCount(4, $item->authorities);
-        $this->assertEquals(
-            [
-                $authorities[0]->id => ['role' => 'after', 'automatically_matched' => true],
-                $authorities[1]->id => ['role' => 'after', 'automatically_matched' => false],
-                $authorities[3]->id => ['role' => 'author', 'automatically_matched' => false],
-                $authorities[4]->id => ['role' => 'after', 'automatically_matched' => true],
-            ],
-            $item->authorities
-                ->pluck('pivot')
-                ->keyBy('authority_id')
-                ->map->only(['role', 'automatically_matched'])
-                ->toArray()
-        );
+        $item->syncMatchedAuthorities([]);
+
+        $this->assertDatabaseMissing('authority_item', [
+            'authority_id' => $authority1->id,
+            'item_id' => $item->id,
+        ]);
+        $this->assertDatabaseHas('authority_item', [
+            'authority_id' => $authority2->id,
+            'item_id' => $item->id,
+            'role' => 'author',
+            'automatically_matched' => false,
+        ]);
+    }
+
+    public function testSyncMatchedAuthoritiesAddsNew()
+    {
+        $item = Item::factory()->create();
+        $authority = Authority::factory()->create();
+
+        $item->syncMatchedAuthorities([
+            $authority->id => ['role' => 'author'],
+        ]);
+
+        $this->assertDatabaseHas('authority_item', [
+            'authority_id' => $authority->id,
+            'item_id' => $item->id,
+            'role' => 'author',
+            'automatically_matched' => true,
+        ]);
     }
 }