diff --git a/.gitignore b/.gitignore
index 1bef60a..5c2bf67 100644
--- a/.gitignore
+++ b/.gitignore
@@ -36,7 +36,7 @@ node_modules/
 jspm_packages/
 
 # Typescript v1 declaration files
-typings/
+# typings/
 
 # Optional npm cache directory
 .npm
diff --git a/src/typings/polyfill.d.ts b/src/typings/polyfill.d.ts
new file mode 100644
index 0000000..cd51876
--- /dev/null
+++ b/src/typings/polyfill.d.ts
@@ -0,0 +1 @@
+declare const getRandomValues: (length: number) => Promise<Uint8Array>;
\ No newline at end of file