Index: trunk/src/org/openstreetmap/josm/data/projection/datum/NTV2SubGrid.java
===================================================================
--- trunk/src/org/openstreetmap/josm/data/projection/datum/NTV2SubGrid.java	(revision 16465)
+++ trunk/src/org/openstreetmap/josm/data/projection/datum/NTV2SubGrid.java	(revision 16466)
@@ -25,4 +25,5 @@
 import java.nio.charset.StandardCharsets;
 import java.util.Arrays;
+import java.util.Objects;
 
 import org.openstreetmap.josm.tools.Logging;
@@ -179,4 +180,5 @@
                 .filter(aSubGrid -> aSubGrid.isCoordWithin(lon, lat))
                 .map(aSubGrid -> aSubGrid.getSubGridForCoord(lon, lat))
+                .filter(Objects::nonNull)
                 .findFirst().orElse(this);
     }