diff --git a/src/activeobjectmgr.h b/src/activeobjectmgr.h
index 369e8acf5..15156a23e 100644
--- a/src/activeobjectmgr.h
+++ b/src/activeobjectmgr.h
@@ -55,7 +55,7 @@ class ActiveObjectMgr
 			for (auto &it : m_active_objects.iter()) {
 				if (!it.second)
 					continue;
-				m_active_objects.remove(it.first);
+				removeObject(it.first);
 			}
 		} while (!m_active_objects.empty());
 	}
diff --git a/src/server/activeobjectmgr.cpp b/src/server/activeobjectmgr.cpp
index e11ba166e..8f48e3081 100644
--- a/src/server/activeobjectmgr.cpp
+++ b/src/server/activeobjectmgr.cpp
@@ -41,7 +41,7 @@ void ActiveObjectMgr::clearIf(const std::function<bool(ServerActiveObject *, u16
 			continue;
 		if (cb(it.second.get(), it.first)) {
 			// Remove reference from m_active_objects
-			m_active_objects.remove(it.first);
+			removeObject(it.first);
 		}
 	}
 }
@@ -94,6 +94,7 @@ bool ActiveObjectMgr::registerObject(std::unique_ptr<ServerActiveObject> obj)
 	auto obj_id = obj->getId(); 
 	m_active_objects.put(obj_id, std::move(obj));
 	m_spatial_index.insert(pos.toArray(), obj_id);
+	assert(m_spatial_index.size() == m_active_objects.size());
 
 	auto new_size = m_active_objects.size();
 	verbosestream << "Server::ActiveObjectMgr::addActiveObjectRaw(): "
diff --git a/src/util/k_d_tree.h b/src/util/k_d_tree.h
index e04f249a6..cca54bdcc 100644
--- a/src/util/k_d_tree.h
+++ b/src/util/k_d_tree.h
@@ -418,7 +418,7 @@ class DynamicKdTrees {
 		trees.at(it->second.tree_idx).remove(it->second.in_tree);
 		del_entries.erase(it);
 		++deleted;
-		if (deleted > n_entries/2) // "shift out" the last tree
+		if (deleted >= (n_entries+1)/2) // "shift out" the last tree
 			shrink_to_half();
 	}
 	void update(const Point &newPos, Id id) {
@@ -431,6 +431,9 @@ class DynamicKdTrees {
 		for (const auto &tree : trees)
 			tree.rangeQuery(min, max, cb);
 	}
+	Idx size() const {
+		return n_entries - deleted;
+	}
 private:
 	void updateDelEntries(uint8_t tree_idx) {
 		trees[tree_idx].foreach([&](Idx in_tree_idx, auto _, Id id) {