diff --git a/src/backends/reference/workloads/Rsqrt.hpp b/src/backends/reference/workloads/Rsqrt.hpp
index 47ebcf3..1b8e6c3 100644
--- a/src/backends/reference/workloads/Rsqrt.hpp
+++ b/src/backends/reference/workloads/Rsqrt.hpp
@@ -9,9 +9,12 @@
 
 namespace armnn
 {
-    template<typename T>
-struct rsqrt : public std::unary_function<T, T>
+template<typename T>
+struct rsqrt
     {
+        typedef T result_type;
+        typedef T argument_type;
+
         T
         operator () (const T&  inputData) const
         {