config: fix leak of default layout namespace

 river/command/layout.zig | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/river/command/layout.zig b/river/command/layout.zig
index da67e82..f75a7ab 100644
--- a/river/command/layout.zig
+++ b/river/command/layout.zig
@@ -48,7 +48,10 @@ pub fn defaultLayout(
     if (args.len < 2) return Error.NotEnoughArguments;
     if (args.len > 2) return Error.TooManyArguments;
 
+    const old_default_layout_namespace = server.config.default_layout_namespace;
     server.config.default_layout_namespace = try util.gpa.dupe(u8, args[1]);
+    util.gpa.free(old_default_layout_namespace);
+
     var it = server.root.all_outputs.first;
     while (it) |node| : (it = node.next) {
         const output = node.data;