diff --git a/drivers/telescope/scopesim_helper.cpp b/drivers/telescope/scopesim_helper.cpp
index b0fef8bb77..210b46397f 100644
--- a/drivers/telescope/scopesim_helper.cpp
+++ b/drivers/telescope/scopesim_helper.cpp
@@ -190,16 +190,21 @@ void Axis::update()         // called about once a second to update the position
         //LOGF_DEBUG("move %s: change %f, position %f", b, change, position.Degrees());
     }
 
+    int rate = std::max(-4,std::min(4,mcRate));
+    if(rate != mcRate) {
+        LOGF_ERROR("Invalid mcRate Detected = %d",mcRate);
+    }
+
     // handle the motion control
-    if (mcRate < 0)
+    if (rate < 0)
     {
-        change = -mcRates[-mcRate].Degrees() * interval;
+        change = -mcRates[-rate].Degrees() * interval;
         //LOGF_DEBUG("mcRate %d, rate %f, change %f", mcRate, mcRates[-mcRate].Degrees(), change);
         position += change;
     }
-    else if (mcRate > 0)
+    else if (rate > 0)
     {
-        change = mcRates[mcRate].Degrees() * interval;
+        change = mcRates[rate].Degrees() * interval;
         //LOGF_DEBUG("mcRate %d, rate %f, change %f", mcRate, mcRates[mcRate].Degrees(), change);
         position += change;
     }
diff --git a/drivers/telescope/scopesim_helper.h b/drivers/telescope/scopesim_helper.h
index 2a3242729f..60021725d2 100644
--- a/drivers/telescope/scopesim_helper.h
+++ b/drivers/telescope/scopesim_helper.h
@@ -288,7 +288,7 @@ class Axis
             guideDuration = 0;
         }
 
-        bool isSlewing;
+        bool isSlewing = false;
 
         bool isTracking()
         {
@@ -328,7 +328,7 @@ class Axis
             return guideDuration > 0;
         }
 
-        int mcRate;             // int -4 to 4 sets move rate, zero is stopped
+        int mcRate = 0;             // int -4 to 4 sets move rate, zero is stopped
 
         void update();         // called about once a second to update the position and mode
 
@@ -346,13 +346,13 @@ class Axis
             0, 0
         };
 
-        bool tracking;      // this allows the tracking state and rate to be set independently
+        bool tracking = false;      // this allows the tracking state and rate to be set independently
 
         AXIS_TRACK_RATE trackingRate { AXIS_TRACK_RATE::OFF };
 
         Angle rotateCentre { 90.0 };
 
-        double guideDuration;
+        double guideDuration = 0;
         Angle guideRateDegSec;
 
         // rates are angles in degrees per second derived from the values in indicom.h