diff --git a/.basedpyright/baseline.json b/.basedpyright/baseline.json
index 6c065401..d297de4c 100644
--- a/.basedpyright/baseline.json
+++ b/.basedpyright/baseline.json
@@ -27537,6 +27537,14 @@
                     "lineCount": 1
                 }
             },
+            {
+                "code": "reportUnknownMemberType",
+                "range": {
+                    "startColumn": 19,
+                    "endColumn": 51,
+                    "lineCount": 1
+                }
+            },
             {
                 "code": "reportUnknownMemberType",
                 "range": {
@@ -27545,6 +27553,14 @@
                     "lineCount": 1
                 }
             },
+            {
+                "code": "reportAttributeAccessIssue",
+                "range": {
+                    "startColumn": 24,
+                    "endColumn": 51,
+                    "lineCount": 1
+                }
+            },
             {
                 "code": "reportAttributeAccessIssue",
                 "range": {
@@ -27553,6 +27569,14 @@
                     "lineCount": 1
                 }
             },
+            {
+                "code": "reportUnknownMemberType",
+                "range": {
+                    "startColumn": 19,
+                    "endColumn": 51,
+                    "lineCount": 1
+                }
+            },
             {
                 "code": "reportUnknownMemberType",
                 "range": {
@@ -27561,6 +27585,14 @@
                     "lineCount": 1
                 }
             },
+            {
+                "code": "reportAttributeAccessIssue",
+                "range": {
+                    "startColumn": 24,
+                    "endColumn": 51,
+                    "lineCount": 1
+                }
+            },
             {
                 "code": "reportAttributeAccessIssue",
                 "range": {
@@ -27569,6 +27601,22 @@
                     "lineCount": 1
                 }
             },
+            {
+                "code": "reportUnknownMemberType",
+                "range": {
+                    "startColumn": 19,
+                    "endColumn": 47,
+                    "lineCount": 1
+                }
+            },
+            {
+                "code": "reportAttributeAccessIssue",
+                "range": {
+                    "startColumn": 24,
+                    "endColumn": 47,
+                    "lineCount": 1
+                }
+            },
             {
                 "code": "reportUnknownMemberType",
                 "range": {
@@ -27617,6 +27665,14 @@
                     "lineCount": 1
                 }
             },
+            {
+                "code": "reportArgumentType",
+                "range": {
+                    "startColumn": 21,
+                    "endColumn": 25,
+                    "lineCount": 1
+                }
+            },
             {
                 "code": "reportCallIssue",
                 "range": {
diff --git a/boxtree/traversal.py b/boxtree/traversal.py
index 7622257f..f20d2c2c 100644
--- a/boxtree/traversal.py
+++ b/boxtree/traversal.py
@@ -70,7 +70,7 @@
 
 # NOTE: Tree cannot go into the TYPE_CHECKING block because it is needed
 # by `dataclass_array_container` (which evals the types)
-from boxtree.tree import Tree  # noqa: TC001
+from boxtree.tree import Tree, TreeOfBoxes  # noqa: TC001
 
 
 if TYPE_CHECKING:
@@ -1760,8 +1760,9 @@ def get_kernel_info(self, *,
                         source_boxes_has_mask: bool,
                         source_parent_boxes_has_mask: bool,
                         debug: bool = False) -> _KernelInfo:
-        # FIXME: not clear this is the right default?
         if particle_id_dtype is None:
+            # This only happens for TreeOfBoxes, where there is no particle info
+            assert not (sources_have_extent or targets_have_extent)
             particle_id_dtype = np.dtype(np.int32)
 
         # {{{ process from_sep_smaller_crit
@@ -1961,7 +1962,7 @@ def get_kernel_info(self, *,
 
     def __call__(self,
                  actx: ArrayContext,
-                 tree: Tree,
+                 tree: Tree | TreeOfBoxes,
                  wait_for: cl.WaitList = None,
                  debug: bool = False,
                  _from_sep_smaller_min_nsources_cumul: int | None = None,