diff --git a/ttnhabbridge/src/main/java/nl/sikken/bertrik/hab/habitat/Location.java b/ttnhabbridge/src/main/java/nl/sikken/bertrik/hab/habitat/Location.java
index 9ce3e31..538772a 100644
--- a/ttnhabbridge/src/main/java/nl/sikken/bertrik/hab/habitat/Location.java
+++ b/ttnhabbridge/src/main/java/nl/sikken/bertrik/hab/habitat/Location.java
@@ -5,9 +5,9 @@ package nl.sikken.bertrik.hab.habitat;
  */
 public final class Location {
 
-    private final Double lat;
-    private final Double lon;
-    private final Double alt;
+    private final double lat;
+    private final double lon;
+    private final double alt;
 
     /**
      * Constructor.
@@ -16,29 +16,29 @@ public final class Location {
      * @param lon longitude (degrees)
      * @param alt altitude (meter)
      */
-    public Location(Double lat, Double lon, Double alt) {
+    public Location(double lat, double lon, double alt) {
         this.lat = lat;
         this.lon = lon;
         this.alt = alt;
     }
 
-    public Double getLat() {
+    public double getLat() {
         return lat;
     }
 
-    public Double getLon() {
+    public double getLon() {
         return lon;
     }
 
-    public Double getAlt() {
+    public double getAlt() {
         return alt;
     }
 
     /**
-     * @return true if this is a fully valid location
+     * @return true if this is a valid location (has latitude and longitude)
      */
     public boolean isValid() {
-        return (lat != null) && (lon != null) && (alt != null);
+        return Double.isFinite(lat) && Double.isFinite(lon);
     }
 
 }
diff --git a/ttnhabbridge/src/main/java/nl/sikken/bertrik/hab/habitat/docs/ListenerInformationDoc.java b/ttnhabbridge/src/main/java/nl/sikken/bertrik/hab/habitat/docs/ListenerInformationDoc.java
index f105ef5..945f48a 100644
--- a/ttnhabbridge/src/main/java/nl/sikken/bertrik/hab/habitat/docs/ListenerInformationDoc.java
+++ b/ttnhabbridge/src/main/java/nl/sikken/bertrik/hab/habitat/docs/ListenerInformationDoc.java
@@ -36,8 +36,11 @@ public final class ListenerInformationDoc extends ListenerDoc {
         ObjectNode node = factory().objectNode();
         node.set("callsign", factory().textNode(receiver.getCallsign()));
         node.set("radio", factory().textNode("TheThingsNetwork"));
-        String antenna = String.format(Locale.US, "%.0f m", receiver.getLocation().getAlt());
-        node.set("antenna", factory().textNode(antenna));
+        double altitude = receiver.getLocation().getAlt();
+        if (Double.isFinite(altitude)) {
+            String antenna = String.format(Locale.ROOT, "%.0f m", altitude);
+            node.set("antenna", factory().textNode(antenna));
+        }
         return node;
     }
 
diff --git a/ttnhabbridge/src/main/java/nl/sikken/bertrik/hab/ttn/TtnMessageGateway.java b/ttnhabbridge/src/main/java/nl/sikken/bertrik/hab/ttn/TtnMessageGateway.java
index 78d5924..4090549 100644
--- a/ttnhabbridge/src/main/java/nl/sikken/bertrik/hab/ttn/TtnMessageGateway.java
+++ b/ttnhabbridge/src/main/java/nl/sikken/bertrik/hab/ttn/TtnMessageGateway.java
@@ -22,13 +22,13 @@ public final class TtnMessageGateway {
     private String time;
     
     @JsonProperty("latitude")
-    private Double latitude = Double.NaN;
+    private double latitude = Double.NaN;
     
     @JsonProperty("longitude")
-    private Double longitude = Double.NaN;
+    private double longitude = Double.NaN;
     
     @JsonProperty("altitude")
-    private Double altitude = Double.NaN;
+    private double altitude = Double.NaN;
 
     private TtnMessageGateway() {
         // jackson constructor
@@ -44,7 +44,7 @@ public final class TtnMessageGateway {
      * @param lon the longitude (degrees)
      * @param alt the altitude (meters)
      */
-    public TtnMessageGateway(String id, boolean trusted, String time, Double lat, Double lon, Double alt) {
+    public TtnMessageGateway(String id, boolean trusted, String time, double lat, double lon, double alt) {
         this();
         this.id = id;
         this.trusted = trusted;
diff --git a/ttnhabbridge/src/test/java/nl/sikken/bertrik/hab/ttn/TtnMessageGatewayTest.java b/ttnhabbridge/src/test/java/nl/sikken/bertrik/hab/ttn/TtnMessageGatewayTest.java
index 48b6867..e8ea9be 100644
--- a/ttnhabbridge/src/test/java/nl/sikken/bertrik/hab/ttn/TtnMessageGatewayTest.java
+++ b/ttnhabbridge/src/test/java/nl/sikken/bertrik/hab/ttn/TtnMessageGatewayTest.java
@@ -46,10 +46,10 @@ public final class TtnMessageGatewayTest {
      */
     @Test
     public void testNoLocation() {
-        TtnMessageGateway gw1 = new TtnMessageGateway("id", true, "time", null, null, null);
+        TtnMessageGateway gw1 = new TtnMessageGateway("id", true, "time", Double.NaN, Double.NaN, Double.NaN);
         Assert.assertFalse(gw1.getLocation().isValid());
 
-        TtnMessageGateway gw2 = new TtnMessageGateway("id", true, "time", null, 1.1, 2.2);
+        TtnMessageGateway gw2 = new TtnMessageGateway("id", true, "time", Double.NaN, 1.1, 2.2);
         Assert.assertFalse(gw2.getLocation().isValid());
     }