diff --git a/src/mjviser/conversions.py b/src/mjviser/conversions.py
index fb1eaf3..7a1527d 100644
--- a/src/mjviser/conversions.py
+++ b/src/mjviser/conversions.py
@@ -582,7 +582,9 @@ def merge_geoms(mj_model: mujoco.MjModel, geom_ids: list[int]) -> trimesh.Trimes
   """Merge multiple geoms into a single trimesh in local body space."""
   meshes = []
   for geom_id in geom_ids:
-    if mj_model.geom_type[geom_id] in (mjtGeom.mjGEOM_MESH, mjtGeom.mjGEOM_SDF):
+    # int() cast: geom_type is a numpy scalar, and `np_scalar in (enum, ...)`
+    # evaluates `enum == np_scalar`, which is False for pybind11 enums.
+    if int(mj_model.geom_type[geom_id]) in (int(mjtGeom.mjGEOM_MESH), int(mjtGeom.mjGEOM_SDF)):
       meshes.append(mujoco_mesh_to_trimesh(mj_model, geom_id))
     else:
       meshes.append(create_primitive_mesh(mj_model, geom_id))
diff --git a/tests/test_conversions.py b/tests/test_conversions.py
index 70fef32..a837c45 100644
--- a/tests/test_conversions.py
+++ b/tests/test_conversions.py
@@ -315,6 +315,15 @@ def test_merge_geoms(simple_model):
   assert len(mesh.vertices) > 0
 
 
+def test_merge_geoms_with_mesh_geom(cubemap_model):
+  # Regression: geom_type is a numpy scalar, and the enum membership test in
+  # merge_geoms silently evaluated False for mesh geoms, raising
+  # "ValueError: Unsupported shape type: 7".
+  mesh = merge_geoms(cubemap_model, [0])
+  assert isinstance(mesh, trimesh.Trimesh)
+  assert len(mesh.vertices) > 0
+
+
 def test_group_geoms_by_visual_compat_splits_textured_hfield():
   xml = """
 <mujoco>