diff --git a/bench/library/benchmark.py b/bench/library/benchmark.py
index 2bb1aa9e..a3e5159c 100644
--- a/bench/library/benchmark.py
+++ b/bench/library/benchmark.py
@@ -1,28 +1,25 @@
 import argparse
 import time
+from contextlib import nullcontext
 
 import numpy as np
 import torch
 from tqdm.auto import tqdm
 
-from quanto.tensor.core import int2, int4, unpack_weights
+from quanto.library import disable_extensions
 
 
 def get_unpack_bench(bits, device):
     qmax = 2**bits
     a = torch.randint(0, qmax, [10240, 10240], dtype=torch.uint8).to(device)
-    bitsdtype = int2 if bits == 2 else int4
 
-    def torch_fn():
-        return unpack_weights(a, bitsdtype)
-
-    def kernel_fn():
+    def bench_fn():
         return torch.ops.quanto.unpack(a, bits)
 
-    return [torch_fn, kernel_fn]
+    return bench_fn
 
 
-def timing(get_bench_functions, device, iterations=10):
+def timing(get_bench_func, device, iterations=10):
     def synchronize(device):
         if device.type == "cuda":
             torch.cuda.synchronize()
@@ -53,15 +50,18 @@ def elapsed_time(self, other):
 
     synchronize(device)
 
+    bench_func = get_bench_func(device)
+    # Warmup to load library
+    bench_func()
     latencies = np.empty((iterations, 2))
     for i in tqdm(range(iterations)):
-        bench_functions = get_bench_functions(device)
-        for j, fn in enumerate(bench_functions):
+        for j, context in enumerate([disable_extensions(), nullcontext()]):
             start_event = timing_event(device)
             end_event = timing_event(device)
             synchronize(device)
             start_event.record()
-            fn()
+            with context:
+                bench_func()
             end_event.record()
             synchronize(device)
             latencies[i, j] = start_event.elapsed_time(end_event)
@@ -92,12 +92,10 @@ def main():
     all_kernels = ["unpack_2bit", "unpack_4bit"]
     kernels = all_kernels if args.kernel is None else [args.kernel]
     for kernel in kernels:
-        get_bench_functions = GET_BENCH_FUNCTIONS[kernel]
-        torch_ms, kernel_ms = timing(get_bench_functions, device, iterations=args.it)
-        ratio = torch_ms / kernel_ms
-        print(
-            f"\n{kernel}[{device.type}]: torch = {torch_ms:.3f} ms, kernel = {kernel_ms:.3f} ms, ratio = {ratio:.1f}x"
-        )
+        get_bench_fn = GET_BENCH_FUNCTIONS[kernel]
+        python_ms, ext_ms = timing(get_bench_fn, device, iterations=args.it)
+        ratio = python_ms / ext_ms
+        print(f"\n{kernel}[{device.type}]: python = {python_ms:.3f} ms, ext = {ext_ms:.3f} ms, ratio = {ratio:.1f}x")
 
 
 if __name__ == "__main__":
diff --git a/quanto/library/ops.py b/quanto/library/ops.py
index 02cf9112..064472e1 100644
--- a/quanto/library/ops.py
+++ b/quanto/library/ops.py
@@ -1,3 +1,4 @@
+import warnings
 from contextlib import contextmanager
 
 import torch
@@ -38,10 +39,16 @@ def define(name, schema):
         torch.library.define(f"{libname}::{name}", schema)
 
     # Provide the inplementation for all dispatch key in the main library
-    @torch.library.impl("quanto::unpack", "default")
+    @torch.library.impl(f"quanto::{name}", "default")
     def impl(*args, **kwargs):
         if _ext_enabled:
-            return getattr(torch.ops.quanto_ext, name)(*args, **kwargs)
+            try:
+                return getattr(torch.ops.quanto_ext, name)(*args, **kwargs)
+            except Exception as e:
+                warnings.warn(
+                    f"A {type(e)} exception occured while calling the optimized kernel for quanto::{name}."
+                    "Falling back to default implementation."
+                )
         return getattr(torch.ops.quanto_py, name)(*args, **kwargs)