diff --git a/lib/DB.zig b/lib/DB.zig
index 9b7f668..0a94175 100644
--- a/lib/DB.zig
+++ b/lib/DB.zig
@@ -548,35 +548,6 @@ test "read/write via iovec" {
     var db = try DB.fromCorpus(allocator, &corpus);
     defer db.deinit(allocator);
 
-    // TODO: replace with an integration test when high-level
-    // reader API is present
-    //const blob = sections.groupmembers.blob;
-    //var i: usize = 0;
-    //while (i < corpus.groups.len) : (i += 1) {
-    //const offset = sections.groupmembers.idx2offset[i];
-    //var vit = try compress.VarintSliceIterator(blob[offset..]);
-    //var it = compress.DeltaDecompressionIterator(&vit);
-    //for (corpus.group2users[i]) |user_idx| {
-    //    const got_user_offset = (try it.next()).?;
-    //    const want_user_offset = sections.users.idx2offset[user_idx];
-    //    try testing.expectEqual(got_user_offset, want_user_offset);
-    //}
-    //try testing.expectEqual(it.next(), null);
-    //}
-
-    //var it = PackedUser.iterator(sections.users.blob, sections.shell_reader);
-    //i = 0;
-    //while (i < corpus.users.len) : (i += 1) {
-    //    const got = (try it.next()).?;
-    //    const user = corpus.users.get(i);
-    //    try testing.expectEqual(user.uid, got.uid());
-    //    try testing.expectEqual(user.gid, got.gid());
-    //    try testing.expectEqualStrings(user.name, got.name());
-    //    try testing.expectEqualStrings(user.gecos, got.gecos());
-    //    try testing.expectEqualStrings(user.home, got.home());
-    //    try testing.expectEqualStrings(user.shell, got.shell(sections.shell_reader));
-    //}
-
     const fd = try os.memfd_create("test_turbonss_db", 0);
     defer os.close(fd);
 
@@ -594,7 +565,7 @@ test "read/write via iovec" {
     try testing.expectEqualSlices(u32, db.idx_uid2user, db2.idx_uid2user[0..num_users]);
 }
 
-test "high-level API" {
+test "getgrnam/getgrgid" {
     var corpus = try Corpus.testCorpus(testing.allocator);
     defer corpus.deinit();
     var db = try DB.fromCorpus(testing.allocator, &corpus);
@@ -627,12 +598,11 @@ test "high-level API" {
 }
 
 test "getgr_bufsize" {
-    var corpus = try Corpus.testCorpus(testing.allocator);
-    defer corpus.deinit();
-    var db = try DB.fromCorpus(testing.allocator, &corpus);
-    defer db.deinit(testing.allocator);
-    var buf = try testing.allocator.alloc(u8, db.header.getgr_bufsize);
-    defer testing.allocator.free(buf);
+    var arena = ArenaAllocator.init(testing.allocator);
+    defer arena.deinit();
+    var corpus = try Corpus.testCorpus(arena.allocator());
+    var db = try DB.fromCorpus(arena.allocator(), &corpus);
+    var buf = try arena.allocator().alloc(u8, db.header.getgr_bufsize);
 
     _ = try db.getgrnam("all", &buf);
     buf.len -= 1;
diff --git a/lib/cgroup.zig b/lib/cgroup.zig
index bb98020..31bc05d 100644
--- a/lib/cgroup.zig
+++ b/lib/cgroup.zig
@@ -3,7 +3,7 @@ const meta = @import("std").meta;
 // Name type should be 0-terminated, members should be null-terminated, but
 // sentinel is not part of the type (but is always there). Adding sentinel
 // crashes zig compiler in pre-0.10. https://github.com/ziglang/zig/issues/7517
-pub const CGroup = struct {
+pub const CGroup = extern struct {
     gid: u32,
     // should be [*:0]const u8
     name: [*]const u8,