diff --git a/src/ApiResource/ProjectionPreviewOutput.php b/src/ApiResource/ProjectionPreviewOutput.php
index 81aa1a1..5ee2799 100644
--- a/src/ApiResource/ProjectionPreviewOutput.php
+++ b/src/ApiResource/ProjectionPreviewOutput.php
@@ -34,7 +34,7 @@ class ProjectionPreviewOutput
 
     public int $totalAllocated;
 
-    public int $unallocated;
+    public ?int $unallocated;
 
     public function __construct(Result $result)
     {
diff --git a/src/Service/Allocation/Result.php b/src/Service/Allocation/Result.php
index 6828d2c..eae5f51 100644
--- a/src/Service/Allocation/Result.php
+++ b/src/Service/Allocation/Result.php
@@ -39,7 +39,7 @@ class Result
         return $this->totalAllocated;
     }
 
-    public function getUnallocated(): int
+    public function getUnallocated(): ?int
     {
         return $this->unallocated;
     }