diff --git a/app/Http/Controllers/BaseAPIController.php b/app/Http/Controllers/BaseAPIController.php
index 2de99be0070b..0219a7f165e4 100644
--- a/app/Http/Controllers/BaseAPIController.php
+++ b/app/Http/Controllers/BaseAPIController.php
@@ -206,6 +206,8 @@ class BaseAPIController extends Controller
                 $data[] = 'clients.contacts';
             } elseif ($include == 'vendors') {
                 $data[] = 'vendors.vendor_contacts';
+            } elseif ($include == 'documents' && $this->entityType == ENTITY_INVOICE) {
+                $data[] = 'documents.expense';
             } elseif ($include) {
                 $data[] = $include;
             }
diff --git a/app/Ninja/Transformers/DocumentTransformer.php b/app/Ninja/Transformers/DocumentTransformer.php
index 0237a306c0de..df412106fae2 100644
--- a/app/Ninja/Transformers/DocumentTransformer.php
+++ b/app/Ninja/Transformers/DocumentTransformer.php
@@ -25,8 +25,8 @@ class DocumentTransformer extends EntityTransformer
             'name' => $document->name,
             'type' => $document->type,
             'path' => $document->path,
-            'invoice_id' => isset($document->invoice->public_id) ? (int) $document->invoice->public_id : null,
-            'expense_id' => isset($document->expense->public_id) ? (int) $document->expense->public_id : null,
+            'invoice_id' => $document->invoice_id && $document->invoice ? (int) $document->invoice->public_id : null,
+            'expense_id' => $document->expense_id && $document->expense ? (int) $document->expense->public_id : null,
             'updated_at' => $this->getTimestamp($document->updated_at),
         ]);
     }
diff --git a/app/Ninja/Transformers/ExpenseTransformer.php b/app/Ninja/Transformers/ExpenseTransformer.php
index 60dbda18851c..5a8317f70daa 100644
--- a/app/Ninja/Transformers/ExpenseTransformer.php
+++ b/app/Ninja/Transformers/ExpenseTransformer.php
@@ -49,6 +49,11 @@ class ExpenseTransformer extends EntityTransformer
     {
         $transformer = new DocumentTransformer($this->account, $this->serializer);
 
+        $expense->documents->each(function ($document) use ($expense) {
+            $document->setRelation('expense', $expense);
+            $document->setRelation('invoice', $expense->invoice);
+        });
+
         return $this->includeCollection($expense->documents, $transformer, ENTITY_DOCUMENT);
     }
 
diff --git a/app/Ninja/Transformers/InvoiceTransformer.php b/app/Ninja/Transformers/InvoiceTransformer.php
index 565991912687..84aa450534a3 100644
--- a/app/Ninja/Transformers/InvoiceTransformer.php
+++ b/app/Ninja/Transformers/InvoiceTransformer.php
@@ -77,6 +77,10 @@ class InvoiceTransformer extends EntityTransformer
     {
         $transformer = new DocumentTransformer($this->account, $this->serializer);
 
+        $invoice->documents->each(function ($document) use ($invoice) {
+            $document->setRelation('invoice', $invoice);
+        });
+
         return $this->includeCollection($invoice->documents, $transformer, ENTITY_DOCUMENT);
     }