diff --git a/lib/std/Progress.zig b/lib/std/Progress.zig
index 3a7bc0d5af..c7dffe4c3f 100644
--- a/lib/std/Progress.zig
+++ b/lib/std/Progress.zig
@@ -734,7 +734,7 @@ const Serialized = struct {
     const Buffer = struct {
         parents: [node_storage_buffer_len]Node.Parent,
         storage: [node_storage_buffer_len]Node.Storage,
-        map: [node_storage_buffer_len]Node.Index,
+        map: [node_storage_buffer_len]Node.OptionalIndex,
 
         parents_copy: [node_storage_buffer_len]Node.Parent,
         storage_copy: [node_storage_buffer_len]Node.Storage,
@@ -753,9 +753,11 @@ fn serialize(serialized_buffer: *Serialized.Buffer) Serialized {
     // Iterate all of the nodes and construct a serializable copy of the state that can be examined
     // without atomics.
     const end_index = @atomicLoad(u32, &global_progress.node_end_index, .monotonic);
-    const node_parents = global_progress.node_parents[0..end_index];
-    const node_storage = global_progress.node_storage[0..end_index];
-    for (node_parents, node_storage, 0..) |*parent_ptr, *storage_ptr, i| {
+    for (
+        global_progress.node_parents[0..end_index],
+        global_progress.node_storage[0..end_index],
+        serialized_buffer.map[0..end_index],
+    ) |*parent_ptr, *storage_ptr, *map| {
         var begin_parent = @atomicLoad(Node.Parent, parent_ptr, .acquire);
         while (begin_parent != .unused) {
             const dest_storage = &serialized_buffer.storage[serialized_len];
@@ -766,12 +768,19 @@ fn serialize(serialized_buffer: *Serialized.Buffer) Serialized {
             if (begin_parent == end_parent) {
                 any_ipc = any_ipc or (dest_storage.getIpcFd() != null);
                 serialized_buffer.parents[serialized_len] = begin_parent;
-                serialized_buffer.map[i] = @enumFromInt(serialized_len);
+                map.* = @enumFromInt(serialized_len);
                 serialized_len += 1;
                 break;
             }
 
             begin_parent = end_parent;
+        } else {
+            // A node may be freed during the execution of this loop, causing
+            // there to be a parent reference to a nonexistent node. Without
+            // this assignment, this would lead to the map entry containing
+            // stale data. By assigning none, the child node with the bad
+            // parent pointer will be harmlessly omitted from the tree.
+            map.* = .none;
         }
     }
 
diff --git a/tools/update_cpu_features.zig b/tools/update_cpu_features.zig
index 0690cc2e69..6d76fc0eb5 100644
--- a/tools/update_cpu_features.zig
+++ b/tools/update_cpu_features.zig
@@ -1038,8 +1038,7 @@ pub fn main() anyerror!void {
     var zig_src_dir = try fs.cwd().openDir(zig_src_root, .{});
     defer zig_src_dir.close();
 
-    var progress = std.Progress{};
-    const root_progress = progress.start("", llvm_targets.len);
+    const root_progress = std.Progress.start(.{ .estimated_total_items = llvm_targets.len });
     defer root_progress.end();
 
     if (builtin.single_threaded) {
@@ -1074,7 +1073,7 @@ const Job = struct {
     llvm_tblgen_exe: []const u8,
     llvm_src_root: []const u8,
     zig_src_dir: std.fs.Dir,
-    root_progress: *std.Progress.Node,
+    root_progress: std.Progress.Node,
     llvm_target: LlvmTarget,
 };
 
@@ -1085,12 +1084,10 @@ fn processOneTarget(job: Job) anyerror!void {
     defer arena_state.deinit();
     const arena = arena_state.allocator();
 
-    var progress_node = job.root_progress.start(llvm_target.zig_name, 3);
-    progress_node.activate();
+    const progress_node = job.root_progress.start(llvm_target.zig_name, 3);
     defer progress_node.end();
 
-    var tblgen_progress = progress_node.start("invoke llvm-tblgen", 0);
-    tblgen_progress.activate();
+    const tblgen_progress = progress_node.start("invoke llvm-tblgen", 0);
 
     const child_args = [_][]const u8{
         job.llvm_tblgen_exe,
@@ -1127,16 +1124,14 @@ fn processOneTarget(job: Job) anyerror!void {
         },
     };
 
-    var json_parse_progress = progress_node.start("parse JSON", 0);
-    json_parse_progress.activate();
+    const json_parse_progress = progress_node.start("parse JSON", 0);
 
     const parsed = try json.parseFromSlice(json.Value, arena, json_text, .{});
     defer parsed.deinit();
     const root_map = &parsed.value.object;
     json_parse_progress.end();
 
-    var render_progress = progress_node.start("render zig code", 0);
-    render_progress.activate();
+    const render_progress = progress_node.start("render zig code", 0);
 
     var features_table = std.StringHashMap(Feature).init(arena);
     var all_features = std.ArrayList(Feature).init(arena);