diff --git a/Changes b/Changes
index 4e95d44..44958ab 100644
--- a/Changes
+++ b/Changes
@@ -1,5 +1,7 @@
-0.56.2 2018-02-07
+0.56.2 2018-02-09
         - [feature] Introduce meta field retrieval method (diewald)
+        - [cleanup] Rename KrillQuery's "_"-method to "nr" to improve
+          compatibility with future versions of Java (diewald)
 
 0.56.1 2018-01-31
         - [bugfix] Changed relation serialization in snippet to work
diff --git a/src/main/java/de/ids_mannheim/korap/query/QueryBuilder.java b/src/main/java/de/ids_mannheim/korap/query/QueryBuilder.java
index f065737..da433ba 100644
--- a/src/main/java/de/ids_mannheim/korap/query/QueryBuilder.java
+++ b/src/main/java/de/ids_mannheim/korap/query/QueryBuilder.java
@@ -402,22 +402,22 @@
 
 
     // Class
-    public SpanClassQueryWrapper _ (byte number, SpanQueryWrapper element) {
+    public SpanClassQueryWrapper nr (byte number, SpanQueryWrapper element) {
         return new SpanClassQueryWrapper(element, number);
     };
 
 
-    public SpanClassQueryWrapper _ (int number, SpanQueryWrapper element) {
+    public SpanClassQueryWrapper nr (int number, SpanQueryWrapper element) {
         return new SpanClassQueryWrapper(element, number);
     };
 
 
-    public SpanClassQueryWrapper _ (short number, SpanQueryWrapper element) {
+    public SpanClassQueryWrapper nr (short number, SpanQueryWrapper element) {
         return new SpanClassQueryWrapper(element, number);
     };
 
 
-    public SpanClassQueryWrapper _ (SpanQueryWrapper element) {
+    public SpanClassQueryWrapper nr (SpanQueryWrapper element) {
         return new SpanClassQueryWrapper(element);
     };
 
diff --git a/src/test/java/de/ids_mannheim/korap/highlight/TestHighlight.java b/src/test/java/de/ids_mannheim/korap/highlight/TestHighlight.java
index 56cf1d3..7a5c550 100644
--- a/src/test/java/de/ids_mannheim/korap/highlight/TestHighlight.java
+++ b/src/test/java/de/ids_mannheim/korap/highlight/TestHighlight.java
@@ -44,7 +44,7 @@
 
         QueryBuilder kq = new QueryBuilder("tokens");
         Result kr = ki
-                .search((SpanQuery) kq.seq(kq._(1, kq.seg("s:b"))).toQuery());
+                .search((SpanQuery) kq.seq(kq.nr(1, kq.seg("s:b"))).toQuery());
         Match km = kr.getMatch(0);
         assertEquals(km.getStartPos(), 1);
         assertEquals(km.getEndPos(), 2);
@@ -54,8 +54,8 @@
                 "<span class=\"context-left\">a</span><span class=\"match\"><mark><mark class=\"class-1 level-0\">b</mark></mark></span><span class=\"context-right\">c</span>",
                 km.getSnippetHTML());
 
-        kr = ki.search((SpanQuery) kq.seq(kq._(1, kq.seg("s:b")))
-                .append(kq._(2, kq.seg("s:c"))).toQuery());
+        kr = ki.search((SpanQuery) kq.seq(kq.nr(1, kq.seg("s:b")))
+                .append(kq.nr(2, kq.seg("s:c"))).toQuery());
         km = kr.getMatch(0);
         assertEquals(km.getStartPos(), 1);
         assertEquals(km.getEndPos(), 3);
@@ -69,8 +69,8 @@
 
 
         kr = ki.search((SpanQuery) kq
-                .seq(kq._(1, kq.seq(kq.seg("s:a")).append(kq.seg("s:b"))))
-                .append(kq._(2, kq.seg("s:c"))).toQuery());
+                .seq(kq.nr(1, kq.seq(kq.seg("s:a")).append(kq.seg("s:b"))))
+                .append(kq.nr(2, kq.seg("s:c"))).toQuery());
         km = kr.getMatch(0);
         assertEquals(km.getStartPos(), 0);
         assertEquals(km.getEndPos(), 3);
@@ -84,12 +84,12 @@
 
 
         kr = ki.search(
-                (SpanQuery) kq._(
+                (SpanQuery) kq.nr(
                         3, kq
-                                .seq(kq._(1,
+                                .seq(kq.nr(1,
                                         kq.seq(kq.seg("s:a"))
                                                 .append(kq.seg("s:b"))))
-                                .append(kq._(2, kq.seg("s:c"))))
+                                .append(kq.nr(2, kq.seg("s:c"))))
                         .toQuery());
         km = kr.getMatch(0);
         assertEquals(km.getStartPos(), 0);
@@ -185,8 +185,8 @@
         ki.commit();
 
         QueryBuilder kq = new QueryBuilder("base");
-        SpanQuery q = (SpanQuery) kq.or(kq._(1, kq.seg("s:a")))
-                .or(kq._(2, kq.seg("s:b"))).toQuery();
+        SpanQuery q = (SpanQuery) kq.or(kq.nr(1, kq.seg("s:a")))
+                .or(kq.nr(2, kq.seg("s:b"))).toQuery();
         Result kr = ki.search(q);
         assertEquals((long) 14, kr.getTotalResults());
         assertEquals("[[{1:a}]]bab", kr.getMatch(0).getSnippetBrackets());
@@ -209,7 +209,7 @@
         assertEquals("ab[[{1:a}]]", kr.getMatch(13).getSnippetBrackets());
 
         kq = new QueryBuilder("base");
-        q = (SpanQuery) kq.or(kq._(1, kq.seg("i:a"))).or(kq._(2, kq.seg("i:c")))
+        q = (SpanQuery) kq.or(kq.nr(1, kq.seg("i:a"))).or(kq.nr(2, kq.seg("i:c")))
                 .toQuery();
         Krill qs = new Krill(q);
         qs.getMeta().getContext().left.setToken(true).setLength((short) 1);
@@ -245,7 +245,7 @@
         assertEquals("... [[{2:a}]]", kr.getMatch(9).getSnippetBrackets());
 
         q = (SpanQuery) kq
-                ._(3, kq.or(kq._(1, kq.seg("i:a"))).or(kq._(2, kq.seg("i:c"))))
+                .nr(3, kq.or(kq.nr(1, kq.seg("i:a"))).or(kq.nr(2, kq.seg("i:c"))))
                 .toQuery();
         qs = new Krill(q);
         qs.getMeta().getContext().left.setToken(true).setLength((short) 0);
diff --git a/src/test/java/de/ids_mannheim/korap/index/TestFieldDocument.java b/src/test/java/de/ids_mannheim/korap/index/TestFieldDocument.java
index 8f418ac..6fe131b 100644
--- a/src/test/java/de/ids_mannheim/korap/index/TestFieldDocument.java
+++ b/src/test/java/de/ids_mannheim/korap/index/TestFieldDocument.java
@@ -116,7 +116,7 @@
 
         QueryBuilder kq = new QueryBuilder("tokens");
         Result kr = ki
-                .search((SpanQuery) kq.seq(kq._(3, kq.seg("s:b"))).toQuery());
+                .search((SpanQuery) kq.seq(kq.nr(3, kq.seg("s:b"))).toQuery());
 
         Match km = kr.getMatch(0);
 
@@ -157,7 +157,7 @@
         // Start creating query
         // within(<s>, {1: {2: [mate/p=ADJA & mate/m=number:sg]}[opennlp/p=NN & tt/p=NN]})
 
-        ks = new Krill(kq.within(kq.tag("base/s:s"), kq._(1,
+        ks = new Krill(kq.within(kq.tag("base/s:s"), kq.nr(1,
                 kq.seq(kq.seg("mate/p:ADJA")).append(kq.seg("opennlp/p:NN")))));
 
         KrillMeta meta = ks.getMeta();
diff --git a/src/test/java/de/ids_mannheim/korap/index/TestMatchIdentifier.java b/src/test/java/de/ids_mannheim/korap/index/TestMatchIdentifier.java
index f74efd8..135c1f9 100644
--- a/src/test/java/de/ids_mannheim/korap/index/TestMatchIdentifier.java
+++ b/src/test/java/de/ids_mannheim/korap/index/TestMatchIdentifier.java
@@ -135,7 +135,7 @@
 
         QueryBuilder kq = new QueryBuilder("tokens");
         Krill ks = new Krill(
-                kq._(2, kq.seq(kq.seg("s:b")).append(kq._(kq.seg("s:a")))));
+                kq.nr(2, kq.seq(kq.seg("s:b")).append(kq.nr(kq.seg("s:a")))));
         Result kr = ki.search(ks);
 
         assertEquals("totalResults", kr.getTotalResults(), 1);
diff --git a/src/test/java/de/ids_mannheim/korap/index/TestMatchIndex.java b/src/test/java/de/ids_mannheim/korap/index/TestMatchIndex.java
index 932d448..756da3f 100644
--- a/src/test/java/de/ids_mannheim/korap/index/TestMatchIndex.java
+++ b/src/test/java/de/ids_mannheim/korap/index/TestMatchIndex.java
@@ -326,8 +326,8 @@
 
         QueryBuilder kq = new QueryBuilder("base");
 
-        SpanQuery sq = kq._(1, kq.seq(kq.seg("s:b")).append(kq.seg("s:a"))
-                .append(kq._(2, kq.seg("s:c")))).toQuery();
+        SpanQuery sq = kq.nr(1, kq.seq(kq.seg("s:b")).append(kq.seg("s:a"))
+                .append(kq.nr(2, kq.seg("s:c")))).toQuery();
 
         kr = ki.search(sq, 0, (short) 20, true, (short) 2, true, (short) 5);
 
diff --git a/src/test/java/de/ids_mannheim/korap/index/TestRealIndex.java b/src/test/java/de/ids_mannheim/korap/index/TestRealIndex.java
index 47a6117..3d22662 100644
--- a/src/test/java/de/ids_mannheim/korap/index/TestRealIndex.java
+++ b/src/test/java/de/ids_mannheim/korap/index/TestRealIndex.java
@@ -42,7 +42,7 @@
         QueryBuilder kq = new QueryBuilder("tokens");
         ks = new Krill(kq
                 .within(kq.tag("base/s:s"),
-                        kq.seq(kq.re("s:.*")).append(kq._(kq.re("s:.*"))))
+                        kq.seq(kq.re("s:.*")).append(kq.nr(kq.re("s:.*"))))
                 .toQuery());
         ks.getMeta().setTimeOut(10000);
         kr = ks.apply(ki);
diff --git a/src/test/java/de/ids_mannheim/korap/index/TestRegexWildcardIndex.java b/src/test/java/de/ids_mannheim/korap/index/TestRegexWildcardIndex.java
index f6e9f17..30a6e10 100644
--- a/src/test/java/de/ids_mannheim/korap/index/TestRegexWildcardIndex.java
+++ b/src/test/java/de/ids_mannheim/korap/index/TestRegexWildcardIndex.java
@@ -364,7 +364,7 @@
         assertEquals((long) 0, kr.getTotalResults());
 
 		// Test with classes
-		sq = kq._(kq.re("s:z.*e")).toQuery();
+		sq = kq.nr(kq.re("s:z.*e")).toQuery();
         assertEquals(
 			"{1: SpanMultiTermQueryWrapper(base:/s:z.*e/)}",
 			sq.toString());
@@ -372,7 +372,7 @@
         assertEquals((long) 0, kr.getTotalResults());
 
 		// Test with nested classes
-		sq = kq.within(kq._(kq.re("s:z.*e")), kq.seg("s:affe")).toQuery();
+		sq = kq.within(kq.nr(kq.re("s:z.*e")), kq.seg("s:affe")).toQuery();
         assertEquals(
 			"spanContain({1: SpanMultiTermQueryWrapper(base:/s:z.*e/)}, base:s:affe)",
 			sq.toString());
@@ -417,7 +417,7 @@
 
 		// Test with multiple distances and a class
 		sq = new SpanMultipleDistanceQuery(
-			kq._(kq.re("s:z.*e")).toQuery(),
+			kq.nr(kq.re("s:z.*e")).toQuery(),
 			kq.seg("s:affe").toQuery(),
 			constraints,
 			true,
diff --git a/src/test/java/de/ids_mannheim/korap/query/TestKrillQuery.java b/src/test/java/de/ids_mannheim/korap/query/TestKrillQuery.java
index 101290d..cb4c5b6 100644
--- a/src/test/java/de/ids_mannheim/korap/query/TestKrillQuery.java
+++ b/src/test/java/de/ids_mannheim/korap/query/TestKrillQuery.java
@@ -140,7 +140,7 @@
     public void KorapClassQuery () throws QueryException {
         QueryBuilder kq = new QueryBuilder("field");
         SpanQuery sq = kq.seq(kq.seg("tree"),
-                kq._(1, kq.contains(kq.tag("s"), kq.tag("np"))), kq.re("hey.*"))
+                kq.nr(1, kq.contains(kq.tag("s"), kq.tag("np"))), kq.re("hey.*"))
                 .toQuery();
         assertEquals(
                 "spanNext(spanNext(field:tree, {1: spanContain(<field:s />, <field:np />)}), SpanMultiTermQueryWrapper(field:/hey.*/))",
@@ -151,7 +151,7 @@
     @Test
     public void KorapClassQuery2 () throws QueryException {
         QueryBuilder kq = new QueryBuilder("field");
-        SpanQuery sq = kq._(kq.seg("base:test")).toQuery();
+        SpanQuery sq = kq.nr(kq.seg("base:test")).toQuery();
         assertEquals("{1: field:base:test}", sq.toString());
     };
 
@@ -160,7 +160,7 @@
     public void KorapClassQuery3 () throws QueryException {
         QueryBuilder kq = new QueryBuilder("field");
         SpanQuery sq = kq.seq(kq.seg("tree"),
-                kq.contains(kq.tag("s"), kq._(kq.tag("np"))), kq.re("hey.*"))
+                kq.contains(kq.tag("s"), kq.nr(kq.tag("np"))), kq.re("hey.*"))
                 .toQuery();
         assertEquals(
                 "spanNext(spanNext(field:tree, spanContain(<field:s />, {1: <field:np />})), SpanMultiTermQueryWrapper(field:/hey.*/))",
@@ -187,7 +187,7 @@
     @Test
     public void KorapShrinkQuery2 () throws QueryException {
         QueryBuilder kq = new QueryBuilder("field");
-        SpanQuery sq = kq.focus(1, kq._(1, kq.tag("np"))).toQuery();
+        SpanQuery sq = kq.focus(1, kq.nr(1, kq.tag("np"))).toQuery();
         assertEquals("focus(1: {1: <field:np />})", sq.toString());
     };
 
@@ -195,8 +195,8 @@
     @Test
     public void KorapShrinkQuery3 () throws QueryException {
         QueryBuilder kq = new QueryBuilder("field");
-        SpanQuery sq = kq.focus(1, kq._(1,
-                kq.seq(kq.tag("np"), kq._(kq.seg("test").without("no")))))
+        SpanQuery sq = kq.focus(1, kq.nr(1,
+                kq.seq(kq.tag("np"), kq.nr(kq.seg("test").without("no")))))
                 .toQuery();
         assertEquals(
                 "focus(1: {1: spanNext(<field:np />, {1: spanNot(field:test, field:no, 0, 0)})})",
@@ -208,7 +208,7 @@
     public void KorapShrinkQuery4 () throws QueryException {
         QueryBuilder kq = new QueryBuilder("field");
         SpanQuery sq = kq.seq(kq.seg("try1"),
-                kq.focus(1, kq._(1, kq.seg("try2"))), kq.seg("try3")).toQuery();
+                kq.focus(1, kq.nr(1, kq.seg("try2"))), kq.seg("try3")).toQuery();
         assertEquals(
                 "spanNext(spanNext(field:try1, focus(1: {1: field:try2})), field:try3)",
                 sq.toString());
diff --git a/src/test/java/de/ids_mannheim/korap/search/TestKrill.java b/src/test/java/de/ids_mannheim/korap/search/TestKrill.java
index 3c4c475..a8b7eaa 100644
--- a/src/test/java/de/ids_mannheim/korap/search/TestKrill.java
+++ b/src/test/java/de/ids_mannheim/korap/search/TestKrill.java
@@ -740,7 +740,7 @@
 
         QueryBuilder kq = new QueryBuilder("tokens");
         Krill ks = new Krill(kq.focus(1,
-                kq.contains(kq.tag("base/s:s"), kq._(1, kq.seg("s:Leben")))));
+                kq.contains(kq.tag("base/s:s"), kq.nr(1, kq.seg("s:Leben")))));
 
         Result kr = ks.apply(ki);
         assertEquals(kr.getSerialQuery(),
@@ -754,7 +754,7 @@
 
         // Try with high class - don't highlight
         ks = new Krill(kq.focus(129,
-                kq.contains(kq.tag("base/s:s"), kq._(129, kq.seg("s:Leben")))));
+                kq.contains(kq.tag("base/s:s"), kq.nr(129, kq.seg("s:Leben")))));
 
         kr = ks.apply(ki);
         assertEquals(kr.getSerialQuery(),
diff --git a/src/test/java/de/ids_mannheim/korap/search/TestResult.java b/src/test/java/de/ids_mannheim/korap/search/TestResult.java
index 7e1442f..7fa390f 100644
--- a/src/test/java/de/ids_mannheim/korap/search/TestResult.java
+++ b/src/test/java/de/ids_mannheim/korap/search/TestResult.java
@@ -51,8 +51,8 @@
         ki.commit();
 
         QueryBuilder kq = new QueryBuilder("base");
-        SpanQuery q = (SpanQuery) kq.or(kq._(1, kq.seg("s:a")))
-                .or(kq._(2, kq.seg("s:b"))).toQuery();
+        SpanQuery q = (SpanQuery) kq.or(kq.nr(1, kq.seg("s:a")))
+                .or(kq.nr(2, kq.seg("s:b"))).toQuery();
         Result kr = ki.search(q);
         assertEquals((long) 7, kr.getTotalResults());