Index: applications/editors/josm/plugins/wikipedia/src/org/wikipedia/WikipediaApp.java
===================================================================
--- applications/editors/josm/plugins/wikipedia/src/org/wikipedia/WikipediaApp.java	(revision 33069)
+++ applications/editors/josm/plugins/wikipedia/src/org/wikipedia/WikipediaApp.java	(revision 33070)
@@ -216,5 +216,7 @@
                     final String wikidata = X_PATH.evaluateString("./@id", node);
                     final String wikipedia = X_PATH.evaluateString("./sitelinks/sitelink/@title", node);
-                    r.put(wikipedia, wikidata);
+                    if (WIKIDATA_PATTERN.matcher(wikidata).matches()) { // non existing entries result in negative integers
+                        r.put(wikipedia, wikidata);
+                    }
                 });
             }
Index: applications/editors/josm/plugins/wikipedia/test/unit/org/wikipedia/WikipediaAppTest.java
===================================================================
--- applications/editors/josm/plugins/wikipedia/test/unit/org/wikipedia/WikipediaAppTest.java	(revision 33069)
+++ applications/editors/josm/plugins/wikipedia/test/unit/org/wikipedia/WikipediaAppTest.java	(revision 33070)
@@ -8,5 +8,4 @@
 import org.wikipedia.data.WikipediaEntry;
 
-import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.Collection;
@@ -116,5 +115,5 @@
         assertThat(map.get("Völs, Tyrol"), is("Q278250"));
         assertThat(map.get("a-non-existing-article"), nullValue());
-        assertThat(map.size(), is(4));
+        assertThat(map.size(), is(3));
     }
 
@@ -124,4 +123,8 @@
                 Stream.iterate("London", x -> x).limit(100).collect(Collectors.toList()));
         assertThat(map, is(Collections.singletonMap("London", "Q84")));
+        final List<String> articles = IntStream.range(0, 200)
+                .mapToObj(i -> "a-non-existing-article-" + i)
+                .collect(Collectors.toList());
+        assertTrue(WikipediaApp.getWikidataForArticles("en", articles).isEmpty());
     }