diff --git a/mlx/transforms.cpp b/mlx/transforms.cpp
index 06bdd1cd3..d91fee91b 100644
--- a/mlx/transforms.cpp
+++ b/mlx/transforms.cpp
@@ -37,7 +37,7 @@ class Synchronizer : public Primitive {
 // are currently under a function transformation and the retain_graph()
 // function which returns true if we are forced to retain the graph during
 // evaluation.
-std::vector<bool> detail::InTracing::trace_stack{};
+std::vector<char> detail::InTracing::trace_stack{};
 int detail::RetainGraph::tracing_counter{0};
 
 array eval_impl(std::vector<array> outputs, bool async) {
diff --git a/mlx/transforms_impl.h b/mlx/transforms_impl.h
index 073957e6b..3aa84bde4 100644
--- a/mlx/transforms_impl.h
+++ b/mlx/transforms_impl.h
@@ -36,7 +36,7 @@ struct InTracing {
   }
 
  private:
-  static std::vector<bool> trace_stack;
+  static std::vector<char> trace_stack;
 };
 
 struct RetainGraph {