diff --git a/src/itree.c b/src/itree.c
index 3098fe1cf45..79e39d6e2ab 100644
--- a/src/itree.c
+++ b/src/itree.c
@@ -145,7 +145,7 @@ struct interval_generator
   ptrdiff_t end;
   uintmax_t otick;              /* A copy of the tree's `otick`.  */
   enum interval_tree_order order;
-  bool_bf running : 1;
+  bool running;
   const char* file;
   int line;
 };