diff --git a/tests/unit/test_umma_qk_hd64.cu b/tests/unit/test_umma_qk_hd64.cu
index 6a671f32..76d88851 100644
--- a/tests/unit/test_umma_qk_hd64.cu
+++ b/tests/unit/test_umma_qk_hd64.cu
@@ -29,7 +29,7 @@ test_umma_qk_hd64(const bf16_t* q, const bf16_t* k,
 {
     const int tid = threadIdx.x;
     const int wid = tid / 32, lane = tid % 32;
-    const int n_ktiles = hd / MMA_K;  // 4 for hd=64
+    const int n_ktiles = 1;  // hd / MMA_K; // Force 1 K-tile for debugging
 
     // SMEM: sQ (128, HD) canonical + sK (128, HD) canonical
     // Each K-tile of (128, 16) = 4096 bytes