diff --git a/README.md b/README.md
index b803f45..11e328a 100644
--- a/README.md
+++ b/README.md
@@ -29,7 +29,9 @@ A library implementing different string similarity and distance measures. A doze
 
 
 ## Download
+
 Using maven:
+
 ```
 <dependency>
     <groupId>info.debatty</groupId>
@@ -40,6 +42,8 @@ Using maven:
 
 Or check the [releases](https://github.com/tdebatty/java-string-similarity/releases).
 
+This library requires Java 8 or more recent.
+
 ## Overview
 
 The main characteristics of each implemented algorithm are presented below. The "cost" column gives an estimation of the computational cost to compute the similarity between two strings of length m and n respectively.
diff --git a/pom.xml b/pom.xml
index 58319b2..3f28866 100644
--- a/pom.xml
+++ b/pom.xml
@@ -82,6 +82,9 @@
                 <groupId>org.apache.maven.plugins</groupId>
                 <artifactId>maven-javadoc-plugin</artifactId>
                 <version>2.10.4</version>
+                <configuration>
+                    <source>8</source>
+                </configuration>
                 <executions>
                     <execution>
                         <id>attach-javadocs</id>
@@ -112,8 +115,8 @@
                 <artifactId>maven-compiler-plugin</artifactId>
                 <version>3.6.1</version>
                 <configuration>
-                    <source>6</source>
-                    <target>1.6</target>
+                    <source>8</source>
+                    <target>8</target>
                 </configuration>
             </plugin>
 
diff --git a/src/main/java/info/debatty/java/stringsimilarity/Cosine.java b/src/main/java/info/debatty/java/stringsimilarity/Cosine.java
index bbdb440..9a7ba0f 100644
--- a/src/main/java/info/debatty/java/stringsimilarity/Cosine.java
+++ b/src/main/java/info/debatty/java/stringsimilarity/Cosine.java
@@ -70,6 +70,7 @@ public Cosine() {
      * @return The cosine similarity in the range [0, 1]
      * @throws NullPointerException if s1 or s2 is null.
      */
+    @Override
     public final double similarity(final String s1, final String s2) {
         if (s1 == null) {
             throw new NullPointerException("s1 must not be null");
@@ -142,12 +143,14 @@ private static double dotProduct(
      * @return 1.0 - the cosine similarity in the range [0, 1]
      * @throws NullPointerException if s1 or s2 is null.
      */
+    @Override
     public final double distance(final String s1, final String s2) {
         return 1.0 - similarity(s1, s2);
     }
 
     /**
-     * {@inheritDoc}
+     * Compute similarity between precomputed profiles.
+     *
      * @param profile1
      * @param profile2
      * @return
diff --git a/src/main/java/info/debatty/java/stringsimilarity/RatcliffObershelp.java b/src/main/java/info/debatty/java/stringsimilarity/RatcliffObershelp.java
index f535d10..22e4ea3 100644
--- a/src/main/java/info/debatty/java/stringsimilarity/RatcliffObershelp.java
+++ b/src/main/java/info/debatty/java/stringsimilarity/RatcliffObershelp.java
@@ -27,7 +27,6 @@
 import info.debatty.java.stringsimilarity.interfaces.NormalizedStringDistance;
 import java.util.List;
 import java.util.ArrayList;
-import java.util.Iterator;
 
 import net.jcip.annotations.Immutable;