diff --git a/dm_control/mujoco/index.py b/dm_control/mujoco/index.py
index 112e4a78..087e7dcf 100644
--- a/dm_control/mujoco/index.py
+++ b/dm_control/mujoco/index.py
@@ -369,10 +369,9 @@ def convert_key_item(self, key_item):
       # representing names. If there is a mix, we will let NumPy throw an error
       # when trying to index with the returned item.
       if isinstance(key_item.flat[0], str):
-        key_item = np.array([self._names_to_offsets[util.to_native_string(k)]
-                             for k in key_item.flat])
-        # Ensure the output shape is the same as that of the input.
-        key_item.shape = original_shape
+        key_item = np.array(
+          [self._names_to_offsets[util.to_native_string(k)] for k in key_item.flat]
+        ).reshape(original_shape)  # Ensure the output shape is the same as that of the input.
 
     return key_item
 
diff --git a/dm_control/mujoco/index_test.py b/dm_control/mujoco/index_test.py
index 3eaeae53..b324041f 100644
--- a/dm_control/mujoco/index_test.py
+++ b/dm_control/mujoco/index_test.py
@@ -347,8 +347,9 @@ def testReadWrite_(self, field):
     # Write unique values to the FieldIndexer and read them back again.
     # Don't write to non-float fields since these might contain pointers.
     if np.issubdtype(old_contents.dtype, np.floating):
-      new_contents = np.arange(old_contents.size, dtype=old_contents.dtype)
-      new_contents.shape = old_contents.shape
+      new_contents = np.arange(
+        old_contents.size, dtype=old_contents.dtype
+      ).reshape(old_contents.shape)
       field[:] = new_contents
       np.testing.assert_array_equal(new_contents, field[:])
 
diff --git a/dm_control/mujoco/wrapper/core_test.py b/dm_control/mujoco/wrapper/core_test.py
index 3489f126..f7b9580b 100644
--- a/dm_control/mujoco/wrapper/core_test.py
+++ b/dm_control/mujoco/wrapper/core_test.py
@@ -552,8 +552,9 @@ def _write_unique_values(self, attr_name, target_array):
     elif (attr_name != "stack"
           and not np.issubdtype(target_array.dtype, np.integer)
           and not np.issubdtype(target_array.dtype, np.bool_)):
-      new_contents = np.arange(target_array.size, dtype=target_array.dtype)
-      new_contents.shape = target_array.shape
+      new_contents = np.arange(
+        target_array.size, dtype=target_array.dtype
+      ).reshape(target_array.shape)
       target_array[:] = new_contents
       np.testing.assert_array_equal(new_contents, target_array[:])