diff --git a/trie4j/pom.xml b/trie4j/pom.xml
index ac787e1..f7771b4 100644
--- a/trie4j/pom.xml
+++ b/trie4j/pom.xml
@@ -2,7 +2,7 @@
   <modelVersion>4.0.0</modelVersion>
   <groupId>com.github.takawitter</groupId>
   <artifactId>trie4j</artifactId>
-  <version>0.9.3</version>
+  <version>0.9.4</version>
   <name>Trie4J</name>
   <packaging>jar</packaging>
   <description>Various TRIE implementation including DoubleArray and LOUDS by Java.</description>
@@ -34,14 +34,6 @@
   </scm>
   <build>
     <plugins>
-      <plugin>
-        <artifactId>maven-compiler-plugin</artifactId>
-        <version>3.0</version>
-        <configuration>
-          <source>1.7</source>
-          <target>1.7</target>
-        </configuration>
-      </plugin>
       <plugin>
         <groupId>org.apache.maven.plugins</groupId>
         <artifactId>maven-javadoc-plugin</artifactId>
@@ -68,6 +60,8 @@
   </build>
   <properties>
     <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
+    <maven.compiler.source>1.7</maven.compiler.source>
+    <maven.compiler.target>1.7</maven.compiler.target>
   </properties>
   <dependencies>
     <dependency>