diff --git a/tests/unit/test_umma_qk.cu b/tests/unit/test_umma_qk.cu
index c6c37367..5544d03b 100644
--- a/tests/unit/test_umma_qk.cu
+++ b/tests/unit/test_umma_qk.cu
@@ -54,9 +54,9 @@ test_umma_qk_hd16(
     // Descriptors
     uint32_t sQ_smem = __cvta_generic_to_shared(sQ);
     uint32_t sK_smem = __cvta_generic_to_shared(sK);
-    uint64_t desc_q = make_umma_desc_kmajor_none(sQ_smem, 128);
-    uint64_t desc_k = make_umma_desc_kmajor_none(sK_smem, 128);
-    uint32_t idesc = 0;  // Try idesc=0 (same as gau-nernst)
+    uint64_t desc_q = make_umma_desc_kmajor_none(sQ_smem, 64);  // Try M=64
+    uint64_t desc_k = make_umma_desc_kmajor_none(sK_smem, 64);  // Try M=64
+    uint32_t idesc = make_idesc(64, 128);  // M=64, N=128
 
     // Verify SMEM Q and K by reading back row 0
     if (tid == 0) {