Index: /trunk/src/org/openstreetmap/josm/io/nmea/NmeaReader.java
===================================================================
--- /trunk/src/org/openstreetmap/josm/io/nmea/NmeaReader.java	(revision 18739)
+++ /trunk/src/org/openstreetmap/josm/io/nmea/NmeaReader.java	(revision 18740)
@@ -433,7 +433,10 @@
                 }
                 // reference ID
-                accu = e[GGA.REF.position];
-                if (!accu.isEmpty()) {
-                    currentwp.put(GpxConstants.PT_DGPSID, accu);
+                if(GGA.REF.position < e.length)
+                {
+                    accu = e[GGA.REF.position];
+                    if (!accu.isEmpty()) {
+                        currentwp.put(GpxConstants.PT_DGPSID, accu);
+                    }
                 }
             } else if (isSentence(e[0], Sentence.VTG)) {