diff --git a/src/openarm_control/qp/arm_joint_limit.py b/src/openarm_control/qp/arm_joint_limit.py
index d25e2805..447c3f62 100644
--- a/src/openarm_control/qp/arm_joint_limit.py
+++ b/src/openarm_control/qp/arm_joint_limit.py
@@ -23,6 +23,13 @@
 import numpy as np
 import numpy.typing as npt
 
+# MuJoCo 3.12 enums no longer compare equal to NumPy scalars, and tuple
+# membership compares element to needle, so keep joint-type checks int-to-int.
+SCALAR_JOINT_TYPES = (
+    int(mujoco.mjtJoint.mjJNT_HINGE),
+    int(mujoco.mjtJoint.mjJNT_SLIDE),
+)
+
 
 class ArmConfigurationLimit(mink.ConfigurationLimit):
     """Apply Mink's configuration limits only to selected scalar arm joints."""
@@ -44,10 +51,7 @@ def __init__(
                 or int(model.jnt_qposadr[joint_id]) not in selected_qpos
             ):
                 continue
-            if model.jnt_type[joint_id] not in (
-                mujoco.mjtJoint.mjJNT_HINGE,
-                mujoco.mjtJoint.mjJNT_SLIDE,
-            ):
+            if int(model.jnt_type[joint_id]) not in SCALAR_JOINT_TYPES:
                 raise ValueError("ArmConfigurationLimit only supports scalar joints.")
             active_dofs.append(int(model.jnt_dofadr[joint_id]))
         self.indices = _readonly(active_dofs, dtype=int)
@@ -106,10 +110,7 @@ def __init__(
                     "its velocity limit will be skipped."
                 )
                 continue
-            if model.jnt_type[joint_id] not in (
-                mujoco.mjtJoint.mjJNT_HINGE,
-                mujoco.mjtJoint.mjJNT_SLIDE,
-            ):
+            if int(model.jnt_type[joint_id]) not in SCALAR_JOINT_TYPES:
                 raise ValueError("ArmJointLimit only supports scalar joints.")
 
             if name is None or name not in velocities:
diff --git a/tests/test_qp_limits.py b/tests/test_qp_limits.py
index adf3fbaf..5177baf5 100644
--- a/tests/test_qp_limits.py
+++ b/tests/test_qp_limits.py
@@ -26,6 +26,7 @@
 
 from openarm_control import ArmSetup, pose_to_se3
 from openarm_control.qp.arm_joint_limit import (
+    SCALAR_JOINT_TYPES,
     ArmConfigurationLimit,
     ArmJointLimit,
 )
@@ -235,3 +236,21 @@ def test_target_does_not_change_geometric_ratio() -> None:
 
     np.testing.assert_allclose(shifted.G, initial.G, atol=1e-12)
     np.testing.assert_allclose(shifted.h, initial.h, atol=1e-12)
+
+
+def test_scalar_joint_types_do_not_rely_on_mujoco_enum_equality() -> None:
+    setup = make_setup("right")
+    selected_qpos = {
+        int(index) for index in setup.joint_resolver.arm_qpos_indices("right")
+    }
+    selected_types = [
+        setup.model.jnt_type[joint_id]
+        for joint_id in range(setup.model.njnt)
+        if int(setup.model.jnt_qposadr[joint_id]) in selected_qpos
+    ]
+    assert selected_types
+
+    assert all(isinstance(joint_type, int) for joint_type in SCALAR_JOINT_TYPES)
+    for joint_type in selected_types:
+        assert int(joint_type) in SCALAR_JOINT_TYPES
+    assert int(mujoco.mjtJoint.mjJNT_FREE) not in SCALAR_JOINT_TYPES