diff --git a/.conda/meta.yaml b/.conda/meta.yaml
index b58ad0f..385895d 100644
--- a/.conda/meta.yaml
+++ b/.conda/meta.yaml
@@ -21,12 +21,12 @@ requirements:
     - scipy
     - setuptools
     - wheel
-    - spm-lab::pylibsparseir >=0.7.0,<0.8.0
+    - spm-lab::pylibsparseir >=0.8.0,<0.9.0
   run:
     - numpy
     - python
     - scipy
-    - spm-lab::pylibsparseir >=0.7.0,<0.8.0
+    - spm-lab::pylibsparseir >=0.8.0,<0.9.0
 
 #test:
 #  imports:
diff --git a/pyproject.toml b/pyproject.toml
index 678ddf4..ccd9e71 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -7,7 +7,7 @@ requires-python = ">=3.10"
 dependencies = [
     "numpy",
     "scipy",
-    "pylibsparseir>=0.7.0,<0.8.0",
+    "pylibsparseir>=0.8.0,<0.9.0",
 ]
 authors = [
     {name = "SpM-lab"}
diff --git a/src/sparse_ir/poly.py b/src/sparse_ir/poly.py
index 41e606d..7e8899f 100644
--- a/src/sparse_ir/poly.py
+++ b/src/sparse_ir/poly.py
@@ -32,6 +32,23 @@ def funcs_get_slice(funcs_ptr, indices):
         raise RuntimeError(f"Failed to get basis function {indices}: {status.value}")
     return FunctionSet(funcs)
 
+def funcs_clone(funcs_ptr):
+    """Clone a function set."""
+    cloned = _lib.spir_funcs_clone(funcs_ptr)
+    if not cloned:
+        raise RuntimeError("Failed to clone function set")
+    return FunctionSet(cloned)
+
+def funcs_deriv(funcs_ptr, n):
+    """Compute the n-th derivative of a function set."""
+    status = c_int()
+    deriv_funcs = _lib.spir_funcs_deriv(funcs_ptr, n, status)
+    if status.value != 0:
+        raise RuntimeError(f"Failed to compute derivative of order {n}: {status.value}")
+    if not deriv_funcs:
+        raise RuntimeError(f"Failed to compute derivative of order {n}")
+    return FunctionSet(deriv_funcs)
+
 def funcs_ft_get_slice(funcs_ptr, indices):
     status = c_int()
     indices = np.asarray(indices, dtype=np.int32)
@@ -134,6 +151,25 @@ def __getitem__(self, index):
 
         return funcs_get_slice(self._ptr, indices)
 
+    def deriv(self, n=1):
+        """Compute the n-th derivative of the basis functions.
+        
+        Args:
+            n (int): Order of the derivative (default: 1)
+            
+        Returns:
+            FunctionSet: New function set representing the n-th derivative
+        """
+        if self._released:
+            raise RuntimeError("Function set has been released")
+        if n < 0:
+            raise ValueError("Derivative order must be non-negative")
+        if n == 0:
+            # Return a clone
+            return funcs_clone(self._ptr)
+            
+        return funcs_deriv(self._ptr, n)
+
     def release(self):
         """Manually release the function set."""
         if not self._released and self._ptr:
@@ -374,6 +410,19 @@ def __getitem__(self, index):
                                              self._xmax, self._period,
                                              self._default_overlap_range)
 
+    def deriv(self, n=1):
+        """Compute the n-th derivative of the basis functions.
+        
+        Args:
+            n (int): Order of the derivative (default: 1)
+            
+        Returns:
+            PiecewiseLegendrePolyVector: New polynomial vector representing the n-th derivative
+        """
+        deriv_funcs = self._funcs.deriv(n)
+        return PiecewiseLegendrePolyVector(deriv_funcs, self._xmin, self._xmax,
+                                          self._period, self._default_overlap_range)
+
 
     def overlap(self, f, xmin: float = None, xmax: float = None, *, rtol=2.3e-16, return_error=False, points=None):
         r"""Evaluate overlap integral of this polynomial with function ``f``.
diff --git a/tests/test_core.py b/tests/test_core.py
index ec4db35..bb8f856 100644
--- a/tests/test_core.py
+++ b/tests/test_core.py
@@ -148,4 +148,4 @@ def test_invalid_parameters(self):
             sve_result_new(kernel, 1e-20)  # Very small epsilon
         except RuntimeError:
             # This is acceptable - very small epsilon might fail
-            pass
\ No newline at end of file
+            pass