diff --git a/src/backends/reference/workloads/RefFillWorkload.hpp b/src/backends/reference/workloads/RefFillWorkload.hpp
index 9be773c..e92514d 100644
--- a/src/backends/reference/workloads/RefFillWorkload.hpp
+++ b/src/backends/reference/workloads/RefFillWorkload.hpp
@@ -15,7 +15,10 @@
 {
 public:
     using BaseWorkload<FillQueueDescriptor>::BaseWorkload;
-    virtual void Execute() const override;
+    void Execute() const override;
+    void ExecuteAsync(WorkingMemDescriptor& workingMemDescriptor)  override;
+private:
+    void Execute(std::vector<ITensorHandle*> outputs) const;
 };
 
 } //namespace armnn