diff --git a/src/liblzma/common/index.c b/src/liblzma/common/index.c
index e897646c..62e4f8ba 100644
--- a/src/liblzma/common/index.c
+++ b/src/liblzma/common/index.c
@@ -202,22 +202,21 @@ index_tree_node_end(index_tree_node *node, const lzma_allocator *allocator,
 	if (node->right != NULL)
 		index_tree_node_end(node->right, allocator, free_func);
 
-	if (free_func != NULL)
-		free_func(node, allocator);
-
-	lzma_free(node, allocator);
+	free_func(node, allocator);
 	return;
 }
 
 
-/// Free the meory allocated for a tree. If free_func is not NULL,
-/// it is called on each node before freeing the node. This is used
-/// to free the Record groups from each index_stream before freeing
-/// the index_stream itself.
+/// Free the memory allocated for a tree. Each node is freed using the
+/// given free_func which is either &lzma_free or &index_stream_end.
+/// The latter is used to free the Record groups from each index_stream
+/// before freeing the index_stream itself.
 static void
 index_tree_end(index_tree *tree, const lzma_allocator *allocator,
 		void (*free_func)(void *node, const lzma_allocator *allocator))
 {
+	assert(free_func != NULL);
+
 	if (tree->root != NULL)
 		index_tree_node_end(tree->root, allocator, free_func);
 
@@ -371,7 +370,8 @@ static void
 index_stream_end(void *node, const lzma_allocator *allocator)
 {
 	index_stream *s = node;
-	index_tree_end(&s->groups, allocator, NULL);
+	index_tree_end(&s->groups, allocator, &lzma_free);
+	lzma_free(s, allocator);
 	return;
 }