diff --git a/build.zig b/build.zig
index ca4bc89..0cdfc88 100644
--- a/build.zig
+++ b/build.zig
@@ -69,23 +69,23 @@ pub fn build(b: *std.Build) void {
     test_step.dependOn(&run_lib_unit_tests.step);
     test_step.dependOn(&run_exe_unit_tests.step);
 
-    const diff = b.addSystemCommand(&.{
-        "git",
-        "diff",
-        "--cached", // see git_add comment
-        "--exit-code",
+    const snapshot_check_mod = b.createModule(.{
+        .root_source_file = b.path("tools/check_snapshots.zig"),
+        .target = target,
+        .optimize = optimize,
     });
-    diff.addDirectoryArg(b.path("snapshots/"));
-
-    test_step.dependOn(&diff.step);
 
-    const git_add = b.addSystemCommand(&.{
-        "git",
-        "add",
-        "snapshots/",
+    const snapshot_check = b.addExecutable(.{
+        .name = "check-snapshots",
+        .root_module = snapshot_check_mod,
     });
 
-    diff.step.dependOn(&git_add.step);
+    const run_snapshot_check = b.addRunArtifact(snapshot_check);
+    run_snapshot_check.stdio = .inherit;
+    run_snapshot_check.has_side_effects = true;
+    run_snapshot_check.addDirectoryArg(b.path("snapshots"));
+    run_snapshot_check.step.dependOn(&run_lib_unit_tests.step);
+    test_step.dependOn(&run_snapshot_check.step);
 }
 
 const std = @import("std");
diff --git a/snapshots/md/single_line_mixed.md b/snapshots/md/single_line_mixed.md
index 44dbf9e..c157fa4 100644
--- a/snapshots/md/single_line_mixed.md
+++ b/snapshots/md/single_line_mixed.md
@@ -1 +1 @@
-**Hello**, world! *italic* underline [s]strike
\ No newline at end of file
+**Hello**, world! *italic* underline ~~strike~~
\ No newline at end of file
diff --git a/snapshots/md/single_line_strikethrough.md b/snapshots/md/single_line_strikethrough.md
new file mode 100644
index 0000000..3212354
--- /dev/null
+++ b/snapshots/md/single_line_strikethrough.md
@@ -0,0 +1 @@
+~~strike~~
\ No newline at end of file
diff --git a/src/formatters/markdown.zig b/src/formatters/markdown.zig
index 2eb0024..d3b405b 100644
--- a/src/formatters/markdown.zig
+++ b/src/formatters/markdown.zig
@@ -7,6 +7,7 @@
 //! ## Supported Conversions
 //! - `[b]text[/b]` → `**text**`
 //! - `[i]text[/i]` → `*text*`
+//! - `[s]text[/s]` → `~~text~~`
 //! - `[url=link]text[/url]` → `[text](link)`
 //! - `[email=addr]text[/email]` → `[text](mailto:addr)`
 //! - `[code]text[/code]` → `` `text` ``
@@ -116,6 +117,7 @@ pub const MarkdownElement = enum {
     list,
     listItem,
     underline,
+    strikethrough,
     noOp,
 };
 
@@ -131,6 +133,7 @@ const element_map = std.StaticStringMap(MarkdownElement).initComptime(&.{
     .{ "list", .list },
     .{ "*", .listItem },
     .{ "u", .underline },
+    .{ "s", .strikethrough },
 });
 
 /// Renders a BBCode document as Markdown text.
@@ -224,6 +227,7 @@ pub fn writeElement(node: Node, element: MarkdownElement, ctx: *const WriteConte
         .list => try writeListElement(node, ctx),
         .listItem => try writeListItemElement(node, ctx),
         .underline => try writeUnderlineElement(node, ctx),
+        .strikethrough => try writeStrikethroughElement(node, ctx),
         .noOp => try writeNoOpElement(node, ctx),
     }
 }
@@ -342,6 +346,12 @@ pub fn writeItalicElement(node: Node, ctx: *const WriteContext) !void {
     try ctx.writer.writeAll("*");
 }
 
+pub fn writeStrikethroughElement(node: Node, ctx: *const WriteContext) !void {
+    try ctx.writer.writeAll("~~");
+    try render(node, ctx);
+    try ctx.writer.writeAll("~~");
+}
+
 pub fn writeCodeElement(node: Node, ctx: *const WriteContext) !void {
     try ctx.writer.writeAll("`");
     try render(node, ctx);
@@ -392,6 +402,31 @@ pub fn writeEmailElement(node: Node, ctx: *const WriteContext) !void {
     }
 }
 
+test "strikethrough" {
+    const cases = [_]struct {
+        bbcode: []const u8,
+        markdown: []const u8,
+    }{
+        .{ .bbcode = "[s]strike[/s]", .markdown = "~~strike~~" },
+        .{ .bbcode = "before [s]strike[/s] after", .markdown = "before ~~strike~~ after" },
+        .{
+            .bbcode = "[s]strike [b]bold[/b] and [i]italic[/i][/s]",
+            .markdown = "~~strike **bold** and *italic*~~",
+        },
+    };
+
+    for (cases) |case| {
+        var document = try Document.loadFromBuffer(testing.allocator, case.bbcode, .{});
+        defer document.deinit();
+
+        var output = std.Io.Writer.Allocating.init(testing.allocator);
+        defer output.deinit();
+
+        try renderDocument(testing.allocator, document, &output.writer, .{});
+        try testing.expectEqualStrings(case.markdown, output.written());
+    }
+}
+
 test render {
     const bbcode_document =
         \\[b]Hello, World![/b]
@@ -489,6 +524,20 @@ test "single lines" {
         try writer.flush();
     }
 
+    {
+        var document = try Document.loadFromBuffer(testing.allocator, "[s]strike[/s]", .{});
+        defer document.deinit();
+
+        var file = try std.Io.Dir.cwd().createFile(testing.io, "snapshots/md/single_line_strikethrough.md", .{});
+        defer file.close(testing.io);
+
+        var buf: [1024]u8 = undefined;
+        var file_writer = file.writer(testing.io, &buf);
+        var writer = &file_writer.interface;
+        try renderDocument(testing.allocator, document, writer, .{});
+        try writer.flush();
+    }
+
     {
         var document = try Document.loadFromBuffer(testing.allocator, "[b]Hello[/b], world! [i]italic[/i] [u]underline[/u] [s]strike[/s]", .{});
         defer document.deinit();
diff --git a/tools/check_snapshots.zig b/tools/check_snapshots.zig
new file mode 100644
index 0000000..069941d
--- /dev/null
+++ b/tools/check_snapshots.zig
@@ -0,0 +1,166 @@
+const std = @import("std");
+
+const RepositoryKind = enum { jj, git, unknown };
+
+pub fn main(init: std.process.Init) !void {
+    const io = init.io;
+    var arena = std.heap.ArenaAllocator.init(init.gpa);
+    defer arena.deinit();
+    const allocator = arena.allocator();
+    const cwd = std.Io.Dir.cwd();
+
+    const repository_kind: RepositoryKind = repository_kind: {
+        cwd.access(io, ".jj", .{}) catch {
+            cwd.access(io, ".git", .{}) catch break :repository_kind .unknown;
+            break :repository_kind .git;
+        };
+        break :repository_kind .jj;
+    };
+
+    switch (repository_kind) {
+        .jj => try checkJjSnapshots(allocator, io, cwd),
+        .git => try checkGitSnapshots(allocator, io),
+        .unknown => {
+            try fatal(io, "No .git or .jj directory found; cannot verify snapshots.\n", .{});
+            std.process.exit(1);
+        },
+    }
+}
+
+fn checkGitSnapshots(allocator: std.mem.Allocator, io: std.Io) !void {
+    _ = try runCapture(allocator, io, &.{ "git", "add", "snapshots/" });
+    _ = try runCapture(allocator, io, &.{ "git", "diff", "--cached", "--exit-code", "snapshots/" });
+}
+
+fn checkJjSnapshots(allocator: std.mem.Allocator, io: std.Io, cwd: std.Io.Dir) !void {
+    const committed_snapshot_paths = try collectCommittedJjSnapshotPaths(allocator, io);
+    const worktree_snapshot_paths = try collectWorktreeSnapshotPaths(allocator, io, cwd);
+
+    const comparePaths = struct {
+        fn lessThan(_: void, lhs: []const u8, rhs: []const u8) bool {
+            return std.mem.lessThan(u8, lhs, rhs);
+        }
+    }.lessThan;
+    std.sort.pdq([]const u8, committed_snapshot_paths.items, {}, comparePaths);
+    std.sort.pdq([]const u8, worktree_snapshot_paths.items, {}, comparePaths);
+
+    const snapshot_path_sets_match = match: {
+        if (committed_snapshot_paths.items.len != worktree_snapshot_paths.items.len) break :match false;
+        for (committed_snapshot_paths.items, worktree_snapshot_paths.items) |committed_path, worktree_path| {
+            if (!std.mem.eql(u8, committed_path, worktree_path)) break :match false;
+        }
+        break :match true;
+    };
+
+    if (!snapshot_path_sets_match) {
+        try fatal(io, "Snapshot file set differs from the current jj commit.\n", .{});
+        try fatal(io, "Committed snapshots:\n", .{});
+        for (committed_snapshot_paths.items) |path| try fatal(io, "  {s}\n", .{path});
+        try fatal(io, "Worktree snapshots:\n", .{});
+        for (worktree_snapshot_paths.items) |path| try fatal(io, "  {s}\n", .{path});
+        std.process.exit(1);
+    }
+
+    for (committed_snapshot_paths.items) |path| {
+        try compareJjSnapshot(allocator, io, cwd, path);
+    }
+}
+
+fn collectCommittedJjSnapshotPaths(allocator: std.mem.Allocator, io: std.Io) !std.ArrayList([]const u8) {
+    const result = try runCapture(allocator, io, &.{
+        "jj",
+        "--ignore-working-copy",
+        "--no-pager",
+        "file",
+        "list",
+        "-r",
+        "@",
+        "snapshots/",
+    });
+
+    var paths: std.ArrayList([]const u8) = .empty;
+    var lines = std.mem.splitScalar(u8, result.stdout, '\n');
+    while (lines.next()) |line| {
+        if (line.len == 0) continue;
+        try paths.append(allocator, try allocator.dupe(u8, line));
+    }
+
+    return paths;
+}
+
+fn collectWorktreeSnapshotPaths(allocator: std.mem.Allocator, io: std.Io, cwd: std.Io.Dir) !std.ArrayList([]const u8) {
+    var snapshots_dir = try cwd.openDir(io, "snapshots", .{ .iterate = true });
+    defer snapshots_dir.close(io);
+
+    var walker = try snapshots_dir.walk(allocator);
+    defer walker.deinit();
+
+    var paths: std.ArrayList([]const u8) = .empty;
+    while (try walker.next(io)) |entry| {
+        if (entry.kind != .file) continue;
+
+        // jj paths always use '/', while the directory walker uses the platform separator.
+        const normalized_relative_path = try allocator.dupe(u8, entry.path);
+        if (std.fs.path.sep != '/') {
+            std.mem.replaceScalar(u8, normalized_relative_path, std.fs.path.sep, '/');
+        }
+
+        const snapshot_path = try std.mem.concat(allocator, u8, &.{ "snapshots/", normalized_relative_path });
+        try paths.append(allocator, snapshot_path);
+    }
+
+    return paths;
+}
+
+fn compareJjSnapshot(allocator: std.mem.Allocator, io: std.Io, cwd: std.Io.Dir, path: []const u8) !void {
+    const expected_result = try runCapture(allocator, io, &.{
+        "jj",
+        "--ignore-working-copy",
+        "--no-pager",
+        "file",
+        "show",
+        "-r",
+        "@",
+        path,
+    });
+    const actual = try cwd.readFileAlloc(io, path, allocator, .unlimited);
+
+    if (!std.mem.eql(u8, expected_result.stdout, actual)) {
+        try fatal(io, "Snapshot differs from the current jj commit: {s}\n", .{path});
+        std.process.exit(1);
+    }
+}
+
+const RunCaptureResult = struct {
+    stdout: []u8,
+    stderr: []u8,
+};
+
+fn runCapture(allocator: std.mem.Allocator, io: std.Io, argv: []const []const u8) !RunCaptureResult {
+    const result = try std.process.run(allocator, io, .{
+        .argv = argv,
+        .stdout_limit = .unlimited,
+        .stderr_limit = .unlimited,
+    });
+
+    // TODO(zig-0.16): Use result.term.success() once Zig 0.16 is removed from CI.
+    const command_succeeded = switch (result.term) {
+        .exited => |code| code == 0,
+        else => false,
+    };
+    if (!command_succeeded) {
+        try fatal(io, "Command failed: {s}\n", .{argv[0]});
+        if (result.stdout.len > 0) try fatal(io, "{s}", .{result.stdout});
+        if (result.stderr.len > 0) try fatal(io, "{s}", .{result.stderr});
+        std.process.exit(1);
+    }
+
+    return .{ .stdout = result.stdout, .stderr = result.stderr };
+}
+
+fn fatal(io: std.Io, comptime fmt: []const u8, args: anytype) !void {
+    var buf: [1024]u8 = undefined;
+    var writer = std.Io.File.stderr().writerStreaming(io, &buf);
+    try writer.interface.print(fmt, args);
+    try writer.interface.flush();
+}