diff --git a/src/backends/cl/workloads/ClSubtractionWorkload.hpp b/src/backends/cl/workloads/ClSubtractionWorkload.hpp
index da6d17c..9f51de6 100644
--- a/src/backends/cl/workloads/ClSubtractionWorkload.hpp
+++ b/src/backends/cl/workloads/ClSubtractionWorkload.hpp
@@ -25,5 +25,6 @@
 
 arm_compute::Status ClSubtractionValidate(const TensorInfo& input0,
                                           const TensorInfo& input1,
-                                          const TensorInfo& output);
+                                          const TensorInfo& output,
+                                          const ActivationDescriptor* activationDescriptor = nullptr);
 } //namespace armnn