diff --git a/tests/unit/test_prefill_t2_debug.cu b/tests/unit/test_prefill_t2_debug.cu
index b4d8e523..d34acebf 100644
--- a/tests/unit/test_prefill_t2_debug.cu
+++ b/tests/unit/test_prefill_t2_debug.cu
@@ -332,7 +332,7 @@ __global__ void prefill_t2_debug_kernel(
         // Read PV result for row qr
         asm volatile("fence.sc.gpu;" ::: "memory");
         __syncthreads();
-        prefill_read_pv_all_subs<HD, N_SUB>(tb, qr, sOacc, p_rescale);
+        prefill_read_pv_all_subs<512, 32>(tb, qr, sOacc, p_rescale);
         __syncthreads();
 
         // Print first few accumulated values
@@ -378,7 +378,7 @@ int main() {
     constexpr int HD = 512;
     constexpr int NOPE = 448;
     constexpr int ROPE = 64;
-    constexpr float scale = 1.0f / sqrtf((float)HD);
+    const float scale = 1.0f / sqrtf((float)HD);
 
     printf("=== Prefill T=2 Debug Test ===\n");
     printf("T=%d N=%d HD=%d NOPE=%d ROPE=%d scale=%.6f\n", T, N, HD, NOPE, ROPE, scale);