diff --git a/build.zig b/build.zig
index f43302b..5398b4b 100644
--- a/build.zig
+++ b/build.zig
@@ -23,6 +23,12 @@ pub fn build(b: *std.Build) !void {
         .target = target,
         .optimize = optimize,
     });
+    const flexilib_dep = b.dependency("flexilib", .{
+        .target = target,
+        .optimize = optimize,
+    });
+    const flexilib_module = flexilib_dep.module("flexilib-interface");
+    lib.addModule("flexilib-interface", flexilib_module);
     // Because we are...well, ourselves, we'll manually override the module
     // root (we are not a module here).
     const ulb = @import("src/universal_lambda_build.zig");
@@ -43,6 +49,7 @@ pub fn build(b: *std.Build) !void {
     });
     _ = try ulb.createOptionsModule(b, main_tests);
 
+    main_tests.addModule("flexilib-interface", flexilib_module);
     var run_main_tests = b.addRunArtifact(main_tests);
     run_main_tests.skip_foreign_checks = true;
 
diff --git a/build.zig.zon b/build.zig.zon
new file mode 100644
index 0000000..85977c1
--- /dev/null
+++ b/build.zig.zon
@@ -0,0 +1,11 @@
+.{
+    .name = "univeral-lambda-zig",
+    .version = "0.5.0",
+
+    .dependencies = .{
+        .flexilib = .{
+            .url = "https://git.lerch.org/lobo/flexilib/archive/0afe78a346959e1206541f5e6170cc1c797bafa3.tar.gz",
+            .hash = "12203158e571bb2fcb0d328049c9fe6cc555d2594377a7d65caf8a5eca50dff7038b",
+        },
+    },
+}
diff --git a/src/flexilib-interface.zig b/src/flexilib-interface.zig
deleted file mode 100644
index 751532e..0000000
--- a/src/flexilib-interface.zig
+++ /dev/null
@@ -1,145 +0,0 @@
-const std = @import("std");
-
-// C interfaces between main and libraries
-pub const Header = extern struct {
-    name_ptr: [*]u8,
-    name_len: usize,
-
-    value_ptr: [*]u8,
-    value_len: usize,
-};
-pub const Response = extern struct {
-    ptr: [*]u8,
-    len: usize,
-
-    headers: [*]Header,
-    headers_len: usize,
-};
-
-pub const Request = extern struct {
-    target: [*]const u8,
-    target_len: usize,
-
-    method: [*:0]u8,
-    method_len: usize,
-
-    content: [*]u8,
-    content_len: usize,
-
-    headers: [*]Header,
-    headers_len: usize,
-};
-
-// If the library is Zig, we can use these helpers
-threadlocal var allocator: ?*std.mem.Allocator = null;
-
-const log = std.log.scoped(.interface);
-
-pub const ZigRequest = struct {
-    target: []const u8,
-    method: [:0]u8,
-    content: []u8,
-    headers: []Header,
-};
-
-pub const ZigHeader = struct {
-    name: []u8,
-    value: []u8,
-};
-
-pub const ZigResponse = struct {
-    body: *std.ArrayList(u8),
-    headers: *std.StringHashMap([]const u8),
-};
-
-pub const ZigRequestHandler = *const fn (std.mem.Allocator, ZigRequest, ZigResponse) anyerror!void;
-
-/// This function is optional and can be exported by zig libraries for
-/// initialization. If exported, it will be called once in the beginning of
-/// a request and will be provided a pointer to std.mem.Allocator, which is
-/// useful for reusing the parent allocator. If you're planning on using
-/// the handleRequest helper below, you must use zigInit or otherwise
-/// set the interface allocator in your own version of zigInit
-pub fn zigInit(parent_allocator: *anyopaque) callconv(.C) void {
-    allocator = @ptrCast(@alignCast(parent_allocator));
-}
-
-pub fn toZigHeader(header: Header) ZigHeader {
-    return .{
-        .name = header.name_ptr[0..header.name_len],
-        .value = header.value_ptr[0..header.value_len],
-    };
-}
-
-/// Converts a StringHashMap to the structure necessary for passing through the
-/// C boundary. This will be called automatically for you via the handleRequest function
-/// and is also used by the main processing loop to coerce request headers
-fn toHeaders(alloc: std.mem.Allocator, headers: std.StringHashMap([]const u8)) ![*]Header {
-    var header_array = try std.ArrayList(Header).initCapacity(alloc, headers.count());
-    var iterator = headers.iterator();
-    while (iterator.next()) |kv| {
-        header_array.appendAssumeCapacity(.{
-            .name_ptr = @constCast(kv.key_ptr.*).ptr,
-            .name_len = kv.key_ptr.*.len,
-
-            .value_ptr = @constCast(kv.value_ptr.*).ptr,
-            .value_len = kv.value_ptr.*.len,
-        });
-    }
-    return header_array.items.ptr;
-}
-
-/// handles a request, implementing the C interface to communicate between the
-/// main program and a zig library. Most importantly, it will catch/report
-/// errors appropriately and allow zig code to use standard Zig error semantics
-pub fn handleRequest(request: *Request, zigRequestHandler: ZigRequestHandler) ?*Response {
-    // TODO: implement another library in C or Rust or something to show
-    // that anything using a C ABI can be successful
-    var alloc = if (allocator) |a| a.* else {
-        log.err("zigInit not called prior to handle_request. This is a coding error", .{});
-        return null;
-    };
-
-    // setup response body
-    var response = std.ArrayList(u8).init(alloc);
-
-    // setup headers
-    var headers = std.StringHashMap([]const u8).init(alloc);
-    zigRequestHandler(
-        alloc,
-        .{
-            .target = request.target[0..request.target_len],
-            .method = request.method[0..request.method_len :0],
-            .content = request.content[0..request.content_len],
-            .headers = request.headers[0..request.headers_len],
-        },
-        .{
-            .body = &response,
-            .headers = &headers,
-        },
-    ) catch |e| {
-        log.err("Unexpected error processing request: {any}", .{e});
-        if (@errorReturnTrace()) |trace| {
-            std.debug.dumpStackTrace(trace.*);
-        }
-        return null;
-    };
-
-    // Marshall data back for handling by server
-
-    var rc = alloc.create(Response) catch {
-        log.err("Could not allocate memory for response object. This may be fatal", .{});
-        return null;
-    };
-    rc.ptr = response.items.ptr;
-    rc.len = response.items.len;
-    rc.headers = toHeaders(alloc, headers) catch |e| {
-        log.err("Unexpected error processing request: {any}", .{e});
-        if (@errorReturnTrace()) |trace| {
-            std.debug.dumpStackTrace(trace.*);
-        }
-        return null;
-    };
-    rc.headers_len = headers.count();
-    return rc;
-}
diff --git a/src/flexilib.zig b/src/flexilib.zig
index 3d211e3..e26e0d0 100644
--- a/src/flexilib.zig
+++ b/src/flexilib.zig
@@ -1,5 +1,5 @@
 const std = @import("std");
-const interface = @import("flexilib-interface.zig"); // TODO: pull in flexilib directly
+const interface = @import("flexilib-interface");
 const testing = std.testing;
 
 const log = std.log.scoped(.@"main-lib");
diff --git a/src/universal_lambda.zig b/src/universal_lambda.zig
index c73a03c..7df29ac 100644
--- a/src/universal_lambda.zig
+++ b/src/universal_lambda.zig
@@ -1,6 +1,6 @@
 const std = @import("std");
 const build_options = @import("build_options");
-const flexilib = @import("flexilib-interface.zig"); // TODO: pull in flexilib directly
+const flexilib = @import("flexilib-interface");
 pub const HandlerFn = *const fn (std.mem.Allocator, []const u8, Context) anyerror![]const u8;
 
 const log = std.log.scoped(.universal_lambda);