arm_compute v19.11
diff --git a/tests/validation/reference/DFT.cpp b/tests/validation/reference/DFT.cpp
index 6ad1b9e..b3c2c6b 100644
--- a/tests/validation/reference/DFT.cpp
+++ b/tests/validation/reference/DFT.cpp
@@ -237,11 +237,11 @@
 template <typename T>
 SimpleTensor<T> complex_mul_and_reduce(const SimpleTensor<T> &input, const SimpleTensor<T> &weights)
 {
-    const int W  = input.shape().x();
-    const int H  = input.shape().y();
-    const int Ci = input.shape().z();
-    const int Co = weights.shape()[3];
-    const int N  = input.shape().total_size() / (W * H * Ci);
+    const uint32_t W  = input.shape().x();
+    const uint32_t H  = input.shape().y();
+    const uint32_t Ci = input.shape().z();
+    const uint32_t Co = weights.shape()[3];
+    const uint32_t N  = input.shape().total_size() / (W * H * Ci);
 
     TensorShape output_shape = input.shape();
     output_shape.set(2, Co);
@@ -250,19 +250,19 @@
     // MemSet dst memory to zero
     std::memset(dst.data(), 0, dst.size());
 
-    for(int b = 0; b < N; ++b)
+    for(uint32_t b = 0; b < N; ++b)
     {
-        for(int co = 0; co < Co; ++co)
+        for(uint32_t co = 0; co < Co; ++co)
         {
-            for(int ci = 0; ci < Ci; ++ci)
+            for(uint32_t ci = 0; ci < Ci; ++ci)
             {
-                for(int h = 0; h < H; ++h)
+                for(uint32_t h = 0; h < H; ++h)
                 {
-                    for(int w = 0; w < W; ++w)
+                    for(uint32_t w = 0; w < W; ++w)
                     {
-                        size_t            i_index  = w + h * W + ci * H * W + b * H * W * Ci;
-                        size_t            w_index  = w + h * W + ci * H * W + co * H * W * Ci;
-                        size_t            o_index  = w + h * W + co * H * W + b * H * W * Co;
+                        const uint32_t    i_index  = w + h * W + ci * H * W + b * H * W * Ci;
+                        const uint32_t    w_index  = w + h * W + ci * H * W + co * H * W * Ci;
+                        const uint32_t    o_index  = w + h * W + co * H * W + b * H * W * Co;
                         const Coordinates i_coords = index2coords(input.shape(), i_index);
                         const Coordinates w_coords = index2coords(weights.shape(), w_index);
                         const Coordinates o_coords = index2coords(dst.shape(), o_index);