diff --git a/src/roboticstoolbox/models/URDF/Fetch.py b/src/roboticstoolbox/models/URDF/Fetch.py
index 9a611355..bfacb126 100644
--- a/src/roboticstoolbox/models/URDF/Fetch.py
+++ b/src/roboticstoolbox/models/URDF/Fetch.py
@@ -1,11 +1,44 @@
 #!/usr/bin/env python
 
+import re
+
 import numpy as np
 from roboticstoolbox.models.URDF.URDFRobot import URDFRobot
 
 # from spatialmath import SE3
 
 
+def _patch_fetch_urdf(text: str) -> str:
+    """Work around a broken upstream file served by robot_descriptions.
+
+    Applies to: robot_descriptions v2.0.0's ``fetch_description``, which
+    clones ``openai/roboschool`` at commit ``c8ee2812`` and exposes
+    ``roboschool/models_robot/fetch_description/robots/fetch.urdf``.
+
+    That file is not well-formed XML: it has a single
+    ``<sensor:camera>...</sensor:camera>`` block (inside a trailing
+    ``<gazebo reference="head_camera_rgb_optical_frame">`` element) using the
+    ``sensor:`` namespace prefix, but no ``xmlns:sensor`` is ever declared
+    anywhere in the document — old pre-SDF Gazebo camera-sensor syntax
+    (circa ROS Fuerte/Groovy) that was never valid XML to begin with.
+    ``roboschool`` is an archived (read-only) GitHub repo, so this can't be
+    fixed upstream. The block is pure Gazebo simulation config (image
+    format/size/FOV/clip planes for a camera plugin) with no bearing on
+    kinematics, dynamics, or geometry, so it's safe to drop entirely.
+
+    If a future robot_descriptions update points at a fixed fork or file,
+    this patch becomes a no-op (the regex simply won't match) — safe to
+    remove once confirmed unnecessary.
+    """
+    return re.sub(
+        r"\s*<gazebo reference=\"head_camera_rgb_optical_frame\">\s*"
+        r"<sensor:camera.*?</sensor:camera>\s*</gazebo>\n?",
+        "\n",
+        text,
+        flags=re.DOTALL,
+    )
+
+
 class Fetch(URDFRobot):
     """
     Class that imports a Fetch URDF model
@@ -34,6 +67,7 @@ def __init__(self):
             "fetch",
             manufacturer="Fetch",
             gripper_link_index=11,
+            patch=_patch_fetch_urdf,
         )
 
         self.qdlim = np.array([4.0, 4.0, 0.1, 1.25, 1.45, 1.57, 1.52, 1.57, 2.26, 2.26])
diff --git a/src/roboticstoolbox/models/URDF/URDFRobot.py b/src/roboticstoolbox/models/URDF/URDFRobot.py
index 565c0550..ad035980 100644
--- a/src/roboticstoolbox/models/URDF/URDFRobot.py
+++ b/src/roboticstoolbox/models/URDF/URDFRobot.py
@@ -12,7 +12,7 @@
 from pathlib import Path
 import importlib
 import warnings
-from typing import TextIO
+from typing import Callable, TextIO
 
 import numpy as np
 from spatialmath import SE3
@@ -258,13 +258,26 @@ def _parse_urdf(urdf_str: str):
     return elinks, urdf.name
 
 
-def URDF_file(file: "str | Path | TextIO", model: "str | None" = None) -> tuple:
+def URDF_file(
+    file: "str | Path | TextIO",
+    model: "str | None" = None,
+    patch: "Callable[[str], str] | None" = None,
+) -> tuple:
     """Parse a URDF or xacro file, return (elinks, name).
 
     ``file`` may be:
     - an absolute or relative path (str or Path) to a .urdf or .xacro file
     - a bare name with no suffix, looked up via robot_descriptions
     - a file-like object whose .read() gives the URDF XML
+
+    ``patch``, if given, is called with the raw file text and must return
+    the text to actually process. It runs *before* xacro processing/XML
+    parsing, so it can surgically correct known-broken third-party source
+    files (e.g. an upstream file with an unexpanded xacro macro that has no
+    definition anywhere in its own repo, or malformed XML) without touching
+    the upstream repo or the bundled `rtb-data` copy. See ``Valkyrie.py``
+    and ``Fetch.py`` for real examples — each documents exactly which
+    upstream bug its patch works around.
     """
     import rtbdata
 
@@ -282,21 +295,32 @@ def URDF_file(file: "str | Path | TextIO", model: "str | None" = None) -> tuple:
         if not file.is_absolute():
             file = xacro_root / file
         resolved_path = file
-        doc = XacroDoc.from_file(file)
+        if patch is not None:
+            # mirrors XacroDoc.from_file()'s own package-discovery step,
+            # since we bypass from_file() here to patch the text first
+            packages.walk_up_from(file)
+            doc = XacroDoc.from_string(patch(file.read_text()), rootdir=file.parent)
+        else:
+            doc = XacroDoc.from_file(file)
     else:
-        doc = XacroDoc.from_string(file.read())
+        text = file.read()
+        if patch is not None:
+            text = patch(text)
+        doc = XacroDoc.from_string(text)
 
     elinks, name = _parse_urdf(doc.to_urdf_string())
     return elinks, name, resolved_path
 
 
-def URDF_read(urdf_path: "str | Path") -> tuple:
+def URDF_read(
+    urdf_path: "str | Path", patch: "Callable[[str], str] | None" = None
+) -> tuple:
     """Load a URDF/xacro file, return (elinks, name, filepath).
 
     ``filepath`` is the resolved filesystem path that was loaded, or None if
-    the source was a file-like object.
+    the source was a file-like object. See ``URDF_file`` for ``patch``.
     """
-    return URDF_file(urdf_path)
+    return URDF_file(urdf_path, patch=patch)
 
 
 class URDFRobot(Robot):
@@ -320,9 +344,10 @@ def __init__(
         urdf_path: "str | Path",
         manufacturer: str = "",
         gripper_link_index: "int | None" = None,
+        patch: "Callable[[str], str] | None" = None,
         **kwargs,
     ):
-        elinks, name, filepath = URDF_file(urdf_path)
+        elinks, name, filepath = URDF_file(urdf_path, patch=patch)
         if gripper_link_index is not None:
             kwargs["gripper_links"] = elinks[gripper_link_index]
         super().__init__(elinks, name=name, manufacturer=manufacturer, **kwargs)
diff --git a/src/roboticstoolbox/models/URDF/Valkyrie.py b/src/roboticstoolbox/models/URDF/Valkyrie.py
index 67d7077b..816fc869 100644
--- a/src/roboticstoolbox/models/URDF/Valkyrie.py
+++ b/src/roboticstoolbox/models/URDF/Valkyrie.py
@@ -1,11 +1,38 @@
 #!/usr/bin/env python
 
+import re
+
 import numpy as np
 from roboticstoolbox.robot.Link import Link
 from roboticstoolbox.robot.Robot import Robot
 from roboticstoolbox.models.URDF.URDFRobot import URDF_read
 
 
+def _patch_valkyrie_urdf(text: str) -> str:
+    """Work around a broken upstream file served by robot_descriptions.
+
+    Applies to: robot_descriptions v2.0.0's ``valkyrie_description``, which
+    clones ``gkjohnson/nasa-urdf-robots`` at commit ``54cdeb1d`` and exposes
+    ``val_description/model/robots/valkyrie_sim.urdf`` as a (supposedly)
+    plain URDF file.
+
+    In reality that file still contains one live, unexpanded xacro macro
+    call: ``<xacro:v1_pelvis_sensors_usb .../>``. There is no definition of
+    this macro anywhere in the entire cloned repo (zero ``.xacro`` files
+    exist in it at all) — it's a gap in the upstream repo itself, not
+    something robot_descriptions or this loader got wrong. The tag is a
+    standalone, self-closing element configuring a simulated pelvis IMU
+    sensor plugin (Gazebo-only, e.g. ``middle_sensor_api_tag``); it isn't
+    nested inside any ``<link>``/``<joint>``, so it has no bearing on
+    kinematics, dynamics, or geometry and is safe to drop entirely.
+
+    If a future robot_descriptions/nasa-urdf-robots update actually defines
+    this macro (or pre-expands it), this patch becomes a no-op (the regex
+    simply won't match) — safe to remove once confirmed unnecessary.
+    """
+    return re.sub(r"\s*<xacro:v1_pelvis_sensors_usb\b[^>]*/>\n?", "\n", text)
+
+
 class Valkyrie(Robot):
     """
     Class that imports a NASA Valkyrie URDF model
@@ -36,7 +63,7 @@ def __init__(self, variant="A"):
         if not variant in "ABCD":
             raise ValueError("variant must be in the range A-D")
 
-        links, name, urdf_filepath = URDF_read("valkyrie")
+        links, name, urdf_filepath = URDF_read("valkyrie", patch=_patch_valkyrie_urdf)
 
         # We wish to add an intermediate link between gripper_r_base and
         # @gripper_r_finger_r/l