diff --git a/pom.xml b/pom.xml
index 7119e63..a9d68f2 100644
--- a/pom.xml
+++ b/pom.xml
@@ -258,7 +258,7 @@
         <dependency>
             <groupId>org.apache.opennlp</groupId>
             <artifactId>opennlp-tools</artifactId>
-            <version>1.9.4</version>
+            <version>2.1.1</version>
         </dependency>
         <dependency>
             <groupId>junit</groupId>
diff --git a/src/main/jpc/jflex/de/ids_mannheim/korap/tokenizer/DerekoDfaTokenizer.jflex b/src/main/jpc/jflex/de/ids_mannheim/korap/tokenizer/DerekoDfaTokenizer.jflex
index c3abeb6..5579b30 100644
--- a/src/main/jpc/jflex/de/ids_mannheim/korap/tokenizer/DerekoDfaTokenizer.jflex
+++ b/src/main/jpc/jflex/de/ids_mannheim/korap/tokenizer/DerekoDfaTokenizer.jflex
@@ -253,6 +253,16 @@
         return sentences.toArray(new Span[0]);
     }
 
+    @Override
+    public String[] sentDetect(CharSequence s) {
+        return sentDetect(s.toString());
+    }
+
+    @Override
+    public Span[] sentPosDetect(CharSequence s) {
+        return sentPosDetect(s.toString());
+    }
+
     public final long yychar() {
         return yychar;
     }