diff --git a/samples/99_matrixexperiments/matrix_helpers.cl b/samples/99_matrixexperiments/matrix_helpers.cl
index 4173a13..6b9df63 100644
--- a/samples/99_matrixexperiments/matrix_helpers.cl
+++ b/samples/99_matrixexperiments/matrix_helpers.cl
@@ -58,49 +58,44 @@ float8 activation(float8 f)
 #define __builtin_expect(x)
 #endif
 
-inline int get_2d_group_linear_id()
+inline uint get_2d_group_linear_id()
 {
-    int lid = (int)get_group_id(1);
-    lid *= (int)get_num_groups(0);
-    lid += (int)get_group_id(0);
+    uint lid = (uint)get_group_id(1);
+    lid *= (uint)get_num_groups(0);
+    lid += (uint)get_group_id(0);
     return lid;
 }
 
 inline int get_swizzled_group_id(int dim)
 {
 #if defined(SWIZZLE_SNAKE)
-    const int max_wg_num = 64;  // number of work-groups in flight to optimize for
-    const int wg_num_n = 8;     // tuneable
-    const int wg_num_m = max_wg_num / wg_num_n;
-    int group_range_n = get_num_groups(0);
-    int wg_repeat_n = group_range_n / wg_num_n;
-    int repeat_id = get_2d_group_linear_id() / max_wg_num;
-    int repeat_id_n = repeat_id % wg_repeat_n;
-    int repeat_id_m = repeat_id / wg_repeat_n;
-    if (dim == 0) {
-        int repeat_start_n_0 = repeat_id_n * wg_num_n;
-        int repeat_start_n_1 = (wg_repeat_n - repeat_id_n - 1) * wg_num_n;
-        int repeat_start_n = (repeat_id_m & 1) == 0 ? repeat_start_n_0 : repeat_start_n_1;
-        int wg_inner_id = get_2d_group_linear_id() % max_wg_num;
-        int wg_coord_n = wg_inner_id % wg_num_n;
-        int start_n_id = repeat_start_n + wg_coord_n;
-        //if (start_n_id >= get_num_groups(0)) {
-        //    printf("ERROR: swizzled group ID(0) is out of range for gid (%d, %d): computed %d, num groups is %d\n",
-        //        (int)get_group_id(0), (int)get_group_id(1), start_n_id, (int)get_num_groups(0));
-        //}
+    const uint max_wg_num = 64;  // number of work-groups in flight to optimize for
+    const uint wg_num_n = 8;     // tuneable
+    const uint wg_num_m = max_wg_num / wg_num_n;
+    uint group_range_n = get_num_groups(0);
+    uint wg_repeat_n = group_range_n / wg_num_n;
+    uint repeat_id = get_2d_group_linear_id() / max_wg_num;
+    uint repeat_id_n = repeat_id % wg_repeat_n;
+    uint repeat_id_m = repeat_id / wg_repeat_n;
+    if (dim == 0 & (uint)get_num_groups(0) >= wg_num_n & (uint)get_num_groups(1) >= wg_num_m) {
+        uint repeat_start_n_0 = repeat_id_n * wg_num_n;
+        uint repeat_start_n_1 = (wg_repeat_n - repeat_id_n - 1) * wg_num_n;
+        uint repeat_start_n = (repeat_id_m & 1) == 0 ? repeat_start_n_0 : repeat_start_n_1;
+        uint wg_inner_id = get_2d_group_linear_id() % max_wg_num;
+        uint wg_coord_n = wg_inner_id % wg_num_n;
+        uint start_n_id = repeat_start_n + wg_coord_n;
         return start_n_id;
     }
-    if (dim == 1) {
-        int repeat_start_m = repeat_id_m * wg_num_m;
-        int wg_inner_id = get_2d_group_linear_id() % max_wg_num;
-        int wg_coord_m = wg_inner_id / wg_num_n;
-        int start_m_id = repeat_start_m + wg_coord_m;
-        //if (start_m_id >= get_num_groups(1)) {
-        //    printf("ERROR: swizzled group ID(1) is out of range for gid (%d, %d): computed %d, num groups is %d\n",
-        //        (int)get_group_id(0), (int)get_group_id(1), start_m_id, (int)get_num_groups(1));
-        //}
+    if (dim == 1 & (uint)get_num_groups(0) >= wg_num_n & (uint)get_num_groups(1) >= wg_num_m) {
+        uint repeat_start_m = repeat_id_m * wg_num_m;
+        uint wg_inner_id = get_2d_group_linear_id() % max_wg_num;
+        uint wg_coord_m = wg_inner_id / wg_num_n;
+        uint start_m_id = repeat_start_m + wg_coord_m;
         return start_m_id;
     }
+    //if (get_group_id(0) < 2 && get_group_id(1) < 2) {
+    //    printf("Fallback: get_group_id() = (%d, %d), get_num_groups() = (%d, %d), wg_num_n = %d, wg_num_m = %d\n", (int)get_group_id(0), (int)get_group_id(1), (int)get_num_groups(0), (int)get_num_groups(1), wg_num_n, wg_num_m);
+    //}
     return get_group_id(dim);
 #else
     return get_group_id(dim);