diff --git a/three/index.d.ts b/three/index.d.ts
index 75c3332ec6..1a691e7878 100644
--- a/three/index.d.ts
+++ b/three/index.d.ts
@@ -669,6 +669,7 @@ declare namespace THREE {
         constructor();
 
         aspect: number;
+        eyeSep: number;
         cameraL: PerspectiveCamera;
         cameraR: PerspectiveCamera;