diff --git a/src/wasm32_bindgen.rs b/src/wasm32_bindgen.rs
index c6eef5fd..86839a09 100644
--- a/src/wasm32_bindgen.rs
+++ b/src/wasm32_bindgen.rs
@@ -58,54 +58,38 @@ pub fn getrandom_inner(dest: &mut [u8]) -> Result<(), Error> {
 }
 
 fn getrandom_init() -> Result<RngSource, Error> {
-    // First up we need to detect if we're running in node.js or a
-    // browser. To do this we get ahold of the `this` object (in a bit
-    // of a roundabout fashion).
-    //
-    // Once we have `this` we look at its `self` property, which is
-    // only defined on the web (either a main window or web worker).
-    let this = Function::new("return this").call(&JsValue::undefined());
-    assert!(this != JsValue::undefined());
-    let this = This::from(this);
-    let is_browser = this.self_() != JsValue::undefined();
-
-    if !is_browser {
-        return Ok(RngSource::Node(node_require("crypto")));
-    }
+    if let Ok(self_) = Global::get_self() {
+        // If `self` is defined then we're in a browser somehow (main window
+        // or web worker). Here we want to try to use
+        // `crypto.getRandomValues`, but if `crypto` isn't defined we assume
+        // we're in an older web browser and the OS RNG isn't available.
+
+        let crypto = self_.crypto();
+        if crypto.is_undefined() {
+            return Err(BINDGEN_CRYPTO_UNDEF);
+        }
 
-    // If `self` is defined then we're in a browser somehow (main window
-    // or web worker). Here we want to try to use
-    // `crypto.getRandomValues`, but if `crypto` isn't defined we assume
-    // we're in an older web browser and the OS RNG isn't available.
-    let crypto = this.crypto();
-    if crypto.is_undefined() {
-        return Err(BINDGEN_CRYPTO_UNDEF);
-    }
+        // Test if `crypto.getRandomValues` is undefined as well
+        let crypto: BrowserCrypto = crypto.into();
+        if crypto.get_random_values_fn().is_undefined() {
+            return Err(BINDGEN_GRV_UNDEF);
+        }
 
-    // Test if `crypto.getRandomValues` is undefined as well
-    let crypto: BrowserCrypto = crypto.into();
-    if crypto.get_random_values_fn().is_undefined() {
-        return Err(BINDGEN_GRV_UNDEF);
+        return Ok(RngSource::Browser(crypto));
     }
 
-    // Ok! `self.crypto.getRandomValues` is a defined value, so let's
-    // assume we can do browser crypto.
-    Ok(RngSource::Browser(crypto))
+    return Ok(RngSource::Node(node_require("crypto")));
 }
 
 #[wasm_bindgen]
 extern "C" {
-    type Function;
-    #[wasm_bindgen(constructor)]
-    fn new(s: &str) -> Function;
-    #[wasm_bindgen(method)]
-    fn call(this: &Function, self_: &JsValue) -> JsValue;
-
-    type This;
-    #[wasm_bindgen(method, getter, structural, js_name = self)]
-    fn self_(me: &This) -> JsValue;
+    type Global;
+    #[wasm_bindgen(getter, catch, static_method_of = Global, js_class = self, js_name = self)]
+    fn get_self() -> Result<Self_, JsValue>;
+
+    type Self_;
     #[wasm_bindgen(method, getter, structural)]
-    fn crypto(me: &This) -> JsValue;
+    fn crypto(me: &Self_) -> JsValue;
 
     #[derive(Clone, Debug)]
     type BrowserCrypto;