diff --git a/_grammar-test/pom.xml b/_grammar-test/pom.xml
index 1bde81d..b8eea52 100644
--- a/_grammar-test/pom.xml
+++ b/_grammar-test/pom.xml
@@ -54,7 +54,7 @@
             </plugin>
             <plugin>
                 <artifactId>maven-compiler-plugin</artifactId>
-                <version>3.6.0</version>
+                <version>3.9.0</version>
                 <configuration>
                     <source>${java.version}</source>
                     <target>${java.version}</target>
diff --git a/pom.xml b/pom.xml
index eefc434..6721460 100644
--- a/pom.xml
+++ b/pom.xml
@@ -48,7 +48,7 @@
 				<plugin>
 					<groupId>org.apache.maven.plugins</groupId>
 					<artifactId>maven-compiler-plugin</artifactId>
-					<version>3.8.1</version>
+					<version>3.9.0</version>
 				</plugin>
 			</plugins>
 		</pluginManagement>