diff --git a/src/hooks/module/useTrestle.js b/src/hooks/module/useTrestle.js
index 29f2d664..9fa75e67 100644
--- a/src/hooks/module/useTrestle.js
+++ b/src/hooks/module/useTrestle.js
@@ -811,7 +811,7 @@ export const useTrestle = () => {
       return -surfaceCompass
     }
 
-    let resultAzimuth = surfaceCompass || moduleCompass
+    let resultAzimuth = moduleCompass
 
 
 
@@ -840,7 +840,7 @@ export const useTrestle = () => {
           if (resultAzimuth > 90) {
             return -180 + (resultAzimuth - 90)
           }
-          return 180 + (90 - resultAzimuth)
+          return 180 + (resultAzimuth - 90)
         } else if (resultAzimuth === 180) {
           return -180 + (resultAzimuth - 90)
         }