diff --git a/README.md b/README.md
index 358d609..8afd68f 100644
--- a/README.md
+++ b/README.md
@@ -16,17 +16,17 @@ const zterm = @import("zterm");
 
 pub fn main() !void {
     var sp = zterm.Spinner{
-        .loading_charset = &[_][]const u8{"⣾", "⣽", "⣻", "⢿", "⡿", "⣟", "⣯", "⣷"},
-        .loading_message = "Selling all your data to the CCP...",
+        .charset = &[_][]const u8{"⣾", "⣽", "⣻", "⢿", "⡿", "⣟", "⣯", "⣷"},
         .finished_charset = "✓",
-        .finished_message = "Lock your doors.",
+        .message = "Selling all your data to the CCP...",
     };
     try sp.start();
 
     time.sleep(3 * time.ns_per_s);
-    var stdOut = std.io.getStdOut();
-    try stdOut.writeAll("\rCalculating very important stuff while selling your data...\n");
+    sp.setMessage("Calculating very important stuff while selling your data...");
+
     time.sleep(2 * time.ns_per_s);
+    sp.setMessage("Sold all your data successfully!");
 
     try sp.stop();
 }
diff --git a/src/Spinner.zig b/src/Spinner.zig
index 70d68d8..4b12a95 100644
--- a/src/Spinner.zig
+++ b/src/Spinner.zig
@@ -5,17 +5,13 @@ const Thread = std.Thread;
 const time = std.time;
 const Spinner = @This();
 
-const default_loading_charset = [_][]const u8{ "|", "/", "-", "\\" };
-const default_finished_charset = "✓";
-
-loading_charset: []const []const u8 = &default_loading_charset,
-loading_message: []const u8 = "",
-
-finished_charset: []const u8 = default_finished_charset,
-finished_message: []const u8 = "",
+// Must be only accessed when thread_lock is held by the current thread.
+charset: []const []const u8 = &[_][]const u8{ "|", "/", "-", "\\" },
+message: []const u8 = "",
 
 keep_going: Atomic(bool) = Atomic(bool).init(false),
 spinner_thread: ?Thread = null,
+thread_lock: Mutex = Mutex{},
 
 framerate_ns: u64 = 100 * time.ns_per_ms,
 
@@ -24,16 +20,37 @@ pub fn start(sp: *Spinner) !void {
     sp.spinner_thread = try Thread.spawn(.{}, writer, .{sp});
 }
 
-pub fn stop(sp: *Spinner) !void {
+pub fn stop(sp: *Spinner, config: struct {
+    charset: ?[]const u8 = null,
+    message: ?[]const u8 = null,
+}) !void {
     sp.keep_going.store(false, .SeqCst);
-    if (sp.spinner_thread) |*thread| thread.join();
+    (sp.spinner_thread orelse unreachable).join();
 
     var stdErr = std.io.getStdErr();
 
+    sp.thread_lock.lock();
+    defer sp.thread_lock.unlock();
+
     try stdErr.writeAll("\r");
-    try stdErr.writeAll(sp.finished_charset);
+    try stdErr.writeAll(config.charset orelse sp.charset[0]);
     try stdErr.writeAll(" ");
-    try stdErr.writeAll(sp.finished_message);
+    try stdErr.writeAll(config.message orelse sp.message);
+    try stdErr.writeAll("\n");
+}
+
+pub fn setCharset(sp: *Spinner, charset: []const []const u8) void {
+    sp.thread_lock.lock();
+    defer sp.thread_lock.unlock();
+
+    sp.charset = charset;
+}
+
+pub fn setMessage(sp: *Spinner, message: []const u8) void {
+    sp.thread_lock.lock();
+    defer sp.thread_lock.unlock();
+
+    sp.message = message;
 }
 
 fn writer(sp: *Spinner) !void {
@@ -41,14 +58,15 @@ fn writer(sp: *Spinner) !void {
     var current_char_idx: usize = 0;
 
     while (true) : (current_char_idx += 1) {
-        if (!sp.keep_going.load(.SeqCst)) break;
-        if (current_char_idx >= sp.loading_charset.len - 1) current_char_idx = 0;
+        if (!sp.keep_going.load(.SeqCst)) return;
+        if (current_char_idx >= sp.charset.len - 1) current_char_idx = 0;
 
-        try stdErr.writeAll("\r");
-
-        try stdErr.writeAll(sp.loading_charset[current_char_idx]);
+        sp.thread_lock.lock();
+        try stdErr.writeAll(sp.charset[current_char_idx]);
         try stdErr.writeAll(" ");
-        try stdErr.writeAll(sp.loading_message);
+        try stdErr.writeAll(sp.message);
+        try stdErr.writeAll("\r");
+        sp.thread_lock.unlock();
 
         time.sleep(sp.framerate_ns);
     }
diff --git a/zterm.zig b/zterm.zig
index 3324e0b..216a620 100644
--- a/zterm.zig
+++ b/zterm.zig
@@ -6,17 +6,17 @@ const zterm = struct {
 
 pub fn main() !void {
     var sp = zterm.Spinner{
-        .loading_charset = &[_][]const u8{"⣾", "⣽", "⣻", "⢿", "⡿", "⣟", "⣯", "⣷"},
-        .loading_message = "Selling all your data to the CCP...",
-        .finished_charset = "✓",
-        .finished_message = "Lock your doors.",
+        .charset = &[_][]const u8{ "⣾", "⣽", "⣻", "⢿", "⡿", "⣟", "⣯", "⣷" },
+        .message = "Selling all your data to the CCP...",
     };
     try sp.start();
 
     time.sleep(3 * time.ns_per_s);
-    var stdOut = std.io.getStdOut();
-    try stdOut.writeAll("\rCalculating very important stuff while selling your data...\n");
-    time.sleep(2 * time.ns_per_s);
+    sp.setMessage("Calculating very important stuff while selling your data...");
 
-    try sp.stop();
+    time.sleep(2 * time.ns_per_s);
+    try sp.stop(.{
+        .charset = "✓",
+        .message = "Successfully sold all your data to the CCP! You data is not in safe hands!",
+    });
 }