diff --git a/src/HrZones.cpp b/src/HrZones.cpp
index 1882eeab4..31d08d2c6 100644
--- a/src/HrZones.cpp
+++ b/src/HrZones.cpp
@@ -440,7 +440,10 @@ int HrZones::whichZone(int rnum, double value) const
         if ((value >= info.lo) && (value < info.hi))
             return j;
     }
-    return -1;
+
+    // if we got here either it is negative, nan, inf or way high
+    if (value < 0 || isnan(value)) return 0;
+    else return range.zones.size()-1;
 }
 
 void HrZones::zoneInfo(int rnum, int znum,
diff --git a/src/RideFile.cpp b/src/RideFile.cpp
index 23d4d9f23..c3911849d 100644
--- a/src/RideFile.cpp
+++ b/src/RideFile.cpp
@@ -341,6 +341,17 @@ void RideFile::appendPoint(double secs, double cad, double hr, double km,
                            double kph, double nm, double watts, double alt,
                            double lon, double lat, double headwind, int interval)
 {
+    // negative values are not good, make them zero
+    // although alt, lat, lon, headwind can be negative of course!
+    if (secs<0) secs=0;
+    if (cad<0) cad=0;
+    if (hr<0) hr=0;
+    if (km<0) km=0;
+    if (kph<0) kph=0;
+    if (nm<0) nm=0;
+    if (watts<0) watts=0;
+    if (interval<0) interval=0;
+
     dataPoints_.append(new RideFilePoint(secs, cad, hr, km, kph,
                                          nm, watts, alt, lon, lat, headwind, interval));
     dataPresent.secs  |= (secs != 0);
diff --git a/src/Zones.cpp b/src/Zones.cpp
index 4147a0f07..9239478b2 100644
--- a/src/Zones.cpp
+++ b/src/Zones.cpp
@@ -437,7 +437,10 @@ int Zones::whichZone(int rnum, double value) const
         if ((value >= info.lo) && (value < info.hi))
             return j;
     }
-    return -1;
+
+    // if we got here either it is negative, nan, inf or way high
+    if (value < 0 || isnan(value)) return 0;
+    else return range.zones.size()-1;
 }
 
 void Zones::zoneInfo(int rnum, int znum,