diff --git a/lib/std/os/emscripten.zig b/lib/std/os/emscripten.zig
index a7fb141ed41b8353e72dd3032fd6486ce9e22ead..67761d3ce57eaf3c49760067901efb6918447d9a 100644
--- a/lib/std/os/emscripten.zig
+++ b/lib/std/os/emscripten.zig
@@ -854,7 +854,7 @@ pub extern "c" fn emscripten_wget(url: [*:0]const u8, file: [*:0]const u8) c_int
 pub extern "c" fn emscripten_wget_data(url: [*:0]const u8, pbuffer: *(?*anyopaque), pnum: *c_int, perror: *c_int) void;
 pub extern "c" fn emscripten_run_script(script: [*:0]const u8) void;
 pub extern "c" fn emscripten_run_script_int(script: [*:0]const u8) c_int;
-pub extern "c" fn emscripten_run_script_string(script: [*:0]const u8) [*:0]u8;
+pub extern "c" fn emscripten_run_script_string(script: [*:0]const u8) ?[*:0]u8;
 pub extern "c" fn emscripten_async_run_script(script: [*:0]const u8, millis: c_int) void;
 pub extern "c" fn emscripten_async_load_script(script: [*:0]const u8, onload: em_callback_func, onerror: em_callback_func) void;
 pub extern "c" fn emscripten_set_main_loop(func: em_callback_func, fps: c_int, simulate_infinite_loop: c_int) void;