diff --git a/src/CelerisLab/lbm/kernels/step/moving_circle.cu b/src/CelerisLab/lbm/kernels/step/moving_circle.cu
index c58fe2d..360f4ee 100644
--- a/src/CelerisLab/lbm/kernels/step/moving_circle.cu
+++ b/src/CelerisLab/lbm/kernels/step/moving_circle.cu
@@ -71,9 +71,11 @@ __global__ void MovingCircleLinks(
     const float q = (float)qd;
     const float rx = (float)__dsub_rn(hx, cx), ry = (float)__dsub_rn(hy, cy);
 
-    // Same fallback rule as build_cut_links (q < 1/2 needs a fluid donor at x - c).
+    // Same two-stage order as build_cut_links + pack_cut_links_to_soa: the fallback
+    // class is chosen from the clamped FP64 q (q < 1/2 needs a fluid donor at x - c);
+    // only then are q, rx, ry rounded to FP32 for the BFL branch and spin velocity.
     unsigned char fallback = CURVED_FALLBACK_BOUZIDI;
-    if (q < 0.5f) {
+    if (qd < 0.5) {
         const int xd = x - ex, yd = y - ey;
         if (xd < 0 || xd >= (int)NX || yd < 0 || yd >= (int)NY || mc_inside(xd, yd, cx, cy, r)
                 || (flag[linear_index((unsigned int)xd, (unsigned int)yd)] & FLAG_FLUID) == 0)