diff --git a/index.d.ts b/index.d.ts
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--- /dev/null
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+// Type definitions for Versor 0.0.4
+// Project: https://github.com/Fil/versor
+// Definitions by: Chris Henrick <https://github.com/clhenrick>
+// Typescript Version: 3.0.3
+
+export as namespace versor;
+
+export = versor;
+
+declare function versor(e: [number, number, number]): [number, number, number];
+
+declare namespace versor {
+  export function cartesian(e: [number, number]): [number, number, number];
+
+  export function rotation(
+    e: [number, number, number, number]
+  ): [number, number, number];
+
+  export function delta(
+    v0: [number, number, number],
+    v1: [number, number, number],
+    alpha?: number
+  ): [number, number, number, number];
+
+  export function multiply(
+    q0: [number, number, number, number],
+    q1: [number, number, number, number]
+  ): [number, number, number, number];
+
+  function cross(
+    v0: [number, number, number],
+    v1: [number, number, number]
+  ): [number, number, number];
+
+  function dot(
+    v0: [number, number, number],
+    v1: [number, number, number]
+  ): number;
+}