diff --git a/app/Transformers/TransactionGroupTransformer.php b/app/Transformers/TransactionGroupTransformer.php
index bbe25538d6..4eaf8bae6a 100644
--- a/app/Transformers/TransactionGroupTransformer.php
+++ b/app/Transformers/TransactionGroupTransformer.php
@@ -336,7 +336,7 @@ class TransactionGroupTransformer extends AbstractTransformer
         $bill            = $this->getBill($journal->bill);
 
         if (null !== $foreignAmount && null !== $foreignCurrency) {
-            $foreignAmount = number_format($foreignAmount, $foreignCurrency['decimal_places'], '.', '');
+            $foreignAmount = number_format((float) $foreignAmount, $foreignCurrency['decimal_places'], '.', '');
         }
 
         return [