diff --git a/apps/magnav/lib.js b/apps/magnav/lib.js
index 443fc91ac..88e8a8426 100644
--- a/apps/magnav/lib.js
+++ b/apps/magnav/lib.js
@@ -24,7 +24,7 @@ exports.calibrate = () => {
 
 exports.tiltfix = (m,g,O,S) => {
   "ram"
-  if (O & S) {
+  if (O && S) {
     m.dx =(m.x-O.x)*S.x; m.dy=(m.y-O.y)*S.y; m.dz=(m.z-O.z)*S.z;
   }
   let d = Math.atan2(-m.dx,m.dy)*180/Math.PI;