diff --git a/Kernel/Heap/SlabAllocator.h b/Kernel/Heap/SlabAllocator.h
index 81d0612fb42..e2fc3a5e7f7 100644
--- a/Kernel/Heap/SlabAllocator.h
+++ b/Kernel/Heap/SlabAllocator.h
@@ -6,6 +6,7 @@
 
 #pragma once
 
+#include <AK/Error.h>
 #include <AK/Function.h>
 #include <AK/Types.h>