diff --git a/csrc/quantization/marlin/sparse/marlin_24_cuda_kernel.cu b/csrc/quantization/marlin/sparse/marlin_24_cuda_kernel.cu
index a33e2660d760e..8fce76eb52f9b 100644
--- a/csrc/quantization/marlin/sparse/marlin_24_cuda_kernel.cu
+++ b/csrc/quantization/marlin/sparse/marlin_24_cuda_kernel.cu
@@ -910,13 +910,16 @@ void marlin_cuda_2_4(const void* A, const void* B, const void* meta, void* C,
       // than better compute utilization
       thread_k = 128;
       thread_m = 128;
-    } else if (prob_n <= 256) {
+    } else {
       thread_k = 64;
       thread_m = 256;
-    } else {
-      thread_k = 32;
-      thread_m = 512;
     }
+    // Also had
+    // if prob_n > 256
+    //   thread_k = 32;
+    //   thread_m = 512;
+    // but this is broken,
+    // TODO(Lucas, Alex M): figure out why
   }
 
   int thread_k_blocks = thread_k / 32;  // 2:4 version with m16n8k32 instruction
@@ -1079,6 +1082,8 @@ torch::Tensor gptq_marlin_24_gemm(torch::Tensor& a, torch::Tensor& b_q_weight,
   // Verify A device and strides
   TORCH_CHECK(a.device().is_cuda(), "A is not on GPU");
   TORCH_CHECK(a.is_contiguous(), "A is not contiguous");
+  TORCH_CHECK(a.dtype() == torch::kFloat16,
+              "A is not float16, currently only float16 is supported");
 
   // Verify B device and strides
   TORCH_CHECK(b_q_weight.device().is_cuda(), "b_q_weight is not on GPU");
@@ -1091,6 +1096,8 @@ torch::Tensor gptq_marlin_24_gemm(torch::Tensor& a, torch::Tensor& b_q_weight,
   // Verify scales device and strides
   TORCH_CHECK(b_scales.device().is_cuda(), "b_scales is not on GPU");
   TORCH_CHECK(b_scales.is_contiguous(), "b_scales is not contiguous");
+  TORCH_CHECK(b_scales.dtype() == torch::kFloat16,
+              "A is not float16, currently only float16 is supported");
 
   // Alloc C matrix
   const at::cuda::OptionalCUDAGuard device_guard(device_of(a));
diff --git a/tests/kernels/test_marlin_gemm.py b/tests/kernels/test_marlin_gemm.py
index 3899ad1a325cf..5e047f4b099f1 100644
--- a/tests/kernels/test_marlin_gemm.py
+++ b/tests/kernels/test_marlin_gemm.py
@@ -50,6 +50,8 @@
     (13, 17, 67),
     (26, 37, 13),
     (67, 13, 11),
+    (257, 13, 11),
+    (658, 13, 11),
 ]
 
 DTYPES = [torch.float16, torch.bfloat16]