diff --git a/lib/Corpus.zig b/lib/Corpus.zig
index 6c87f82..112c19b 100644
--- a/lib/Corpus.zig
+++ b/lib/Corpus.zig
@@ -86,7 +86,7 @@ pub fn init(
         members.len = 0;
 
         for (groupmembers) |member_name| {
-            if (name2user.get(member_name)) |user_idx| {
+            if (name2user.get(member_name.?)) |user_idx| {
                 members.len += 1;
                 members[members.len - 1] = user_idx;
                 try user2groups[user_idx].append(allocator, @intCast(u32, i));
@@ -203,10 +203,10 @@ pub fn testCorpus(allocator: Allocator) !Corpus {
         .shell = "/usr/sbin/nologin",
     } };
 
-    var members0 = &[_][]const u8{"root"};
-    var members1 = &[_][]const u8{"vidmantas"};
-    var members2 = &[_][]const u8{ "svc-bar", "vidmantas" };
-    var members3 = &[_][]const u8{ "svc-bar", "Name" ** 8, "vidmantas", "root" };
+    var members0 = &[_:null]?[:0]const u8{"root"};
+    var members1 = &[_:null]?[:0]const u8{"vidmantas"};
+    var members2 = &[_:null]?[:0]const u8{ "svc-bar", "vidmantas" };
+    var members3 = &[_:null]?[:0]const u8{ "svc-bar", "Name" ** 8, "vidmantas", "root" };
 
     const groups = [_]Group{
         Group{ .gid = 0, .name = "root", .members = members0 },
diff --git a/lib/Group.zig b/lib/Group.zig
index ab8aaab..40c161c 100644
--- a/lib/Group.zig
+++ b/lib/Group.zig
@@ -6,43 +6,33 @@ const Allocator = mem.Allocator;
 const Group = @This();
 
 gid: u32,
-name: []const u8,
-members: []const []const u8,
-_members_buf: []const u8 = undefined,
+name: [:0]const u8,
+//
+members: [:null]const ?[:0]const u8,
 
 pub fn clone(self: *const Group, allocator: Allocator) Allocator.Error!Group {
-    const total_members_len = blk: {
-        var sum: usize = 0;
-        for (self.members) |member| sum += member.len;
-        break :blk sum;
-    };
-    var members = try allocator.alloc([]const u8, self.members.len);
+    var members = try allocator.allocSentinel(?[:0]const u8, self.members.len, null);
     errdefer allocator.free(members);
     members.len = self.members.len;
 
-    var buf = try allocator.alloc(u8, total_members_len);
-    errdefer allocator.free(buf);
-    buf.len = 0;
-
     for (self.members) |member, i| {
-        const old_len = buf.len;
-        buf.len += member.len;
-        mem.copy(u8, buf[old_len..], member);
-        members[i] = buf[old_len..buf.len];
+        const member_name = member.?;
+        members[i] = try allocator.dupeZ(u8, member_name);
     }
 
     return Group{
         .gid = self.gid,
-        .name = try allocator.dupe(u8, self.name),
+        .name = try allocator.dupeZ(u8, self.name),
         .members = members,
-        ._members_buf = buf,
     };
 }
 
 pub fn deinit(self: *Group, allocator: Allocator) void {
     allocator.free(self.name);
+    for (self.members) |member| {
+        allocator.free(member.?);
+    }
     allocator.free(self.members);
-    allocator.free(self._members_buf);
     self.* = undefined;
 }
 
@@ -50,13 +40,13 @@ const testing = std.testing;
 
 test "Group.clone" {
     // TODO: how to do this on stack?
-    var member1 = try testing.allocator.dupe(u8, "member1");
+    var member1 = try testing.allocator.dupeZ(u8, "member1");
     defer testing.allocator.free(member1);
 
     var group = Group{
         .gid = 1,
         .name = "foo",
-        .members = &[_][]const u8{ member1, "member2" },
+        .members = &[_:null]?[:0]const u8{ member1, "member2", null },
     };
 
     var cloned = try group.clone(testing.allocator);
@@ -67,5 +57,5 @@ test "Group.clone" {
     member1[0] = 'x';
     try testing.expectEqual(cloned.gid, 1);
     try testing.expectEqualSlices(u8, cloned.name, "foo");
-    try testing.expectEqualSlices(u8, cloned.members[0], "member1");
+    try testing.expectEqualSlices(u8, cloned.members[0].?, "member1");
 }