diff --git a/sha1/index.d.ts b/sha1/index.d.ts
new file mode 100644
index 0000000000..3fbc990b23
--- /dev/null
+++ b/sha1/index.d.ts
@@ -0,0 +1,15 @@
+// Type definitions for sha1 v1.1.1
+// Project: https://github.com/pvorb/node-sha1
+// Definitions adapted from md5 definitions by: Bill Sourour <https://github.com/arcdev1>
+// Definitions: https://github.com/DefinitelyTyped/DefinitelyTyped
+
+/// <reference types="node" />
+
+/**
+ * js function for hashing messages with SHA1
+ * 
+ * @param {(string | Buffer)} message - a string or buffer to hash
+ * @returns {string} the resultant SHA1 hash of the given message
+ */
+declare function main(message: string | Buffer): string;
+export = main;