diff --git a/src/index.ts b/src/index.ts
index 3bd3e06..7f084f6 100644
--- a/src/index.ts
+++ b/src/index.ts
@@ -85,7 +85,7 @@ export class GLMouse {
 
     private _handleMouseWheel = (ev:any) => {
         ev.preventDefault();
-        this._radius -= ev.deltaY * this.wheelSpeed;
+        this._radius -= ev.deltaY * this.wheelSpeed * Math.max(1, this._radius / 100);
     }
 
     private _lastX:number = 0;
@@ -143,4 +143,4 @@ function getCircleCoord (lat, lon, r) : vec3{
 
 function getAngle (a:[number, number], b:[number, number]) {
     return Math.atan2(b[1], b[0]) - Math.atan2(a[1], a[0]);
-}
\ No newline at end of file
+}