diff --git a/src/alphafold3/model/components/mapping.py b/src/alphafold3/model/components/mapping.py
index e315649..44ab109 100644
--- a/src/alphafold3/model/components/mapping.py
+++ b/src/alphafold3/model/components/mapping.py
@@ -12,7 +12,7 @@
 
 from collections.abc import Callable, Sequence
 import functools
-from typing import Any
+from typing import Any, TypeVar
 
 import haiku as hk
 import jax
@@ -25,6 +25,8 @@ PytreeJaxArray = Any
 partial = functools.partial
 PROXY = object()
 
+T = TypeVar("T")
+
 
 def _maybe_slice(array, i, slice_size, axis):
   if axis is PROXY:
@@ -82,6 +84,16 @@ def sharded_map(
     return sharded_apply(vmapped_fun, shard_size, in_axes, out_axes)
 
 
+def _set_docstring(docstr: str) -> Callable[[T], T]:
+  """Decorator for setting the docstring of a function."""
+
+  def wrapped(fun: T) -> T:
+    fun.__doc__ = docstr.format(fun=getattr(fun, "__name__", repr(fun)))
+    return fun
+
+  return wrapped
+
+
 def sharded_apply(
     fun: Callable[..., PytreeJaxArray],
     shard_size: int | None = 1,
@@ -120,7 +132,8 @@ def sharded_apply(
   if shard_size is None:
     return fun
 
-  @jax.util.wraps(fun, docstr=docstr)
+  @_set_docstring(docstr)
+  @functools.wraps(fun)
   def mapped_fn(*args, **kwargs):
     # Expand in axes and determine loop range.
     in_axes_ = _expand_axes(in_axes, args)