diff --git a/README.md b/README.md
index 816c8ab..20f4b10 100644
--- a/README.md
+++ b/README.md
@@ -275,6 +275,7 @@ Then, in your `build.zig`'s `build` function, add the following before
     const zap = b.dependency("zap", .{
         .target = target,
         .optimize = optimize,
+        //.openssl = true, // required to use tls
     });
     exe.addModule("zap", zap.module("zap"));
     exe.linkLibrary(zap.artifact("facil.io"));
diff --git a/build.zig b/build.zig
index 8090aa9..60f235b 100644
--- a/build.zig
+++ b/build.zig
@@ -8,7 +8,7 @@ pub fn build(b: *std.Build) !void {
     const optimize = b.standardOptimizeOption(.{});
 
     // Use an os env var to determine whether to build openssl support
-    const use_openssl = blk: {
+    const use_openssl = b.option(bool, "openssl", "Use system-installed openssl for TLS support in zap") orelse blk: {
         if (std.os.getenv("ZAP_USE_OPENSSL")) |val| {
             if (std.mem.eql(u8, val, "true")) break :blk true;
         }