diff --git a/pom.xml b/pom.xml
index 45e3a7d..e729e11 100644
--- a/pom.xml
+++ b/pom.xml
@@ -125,8 +125,7 @@
           <headerLocation>src/main/resources/copyright_header.txt</headerLocation>
           <includeTestSourceDirectory>true</includeTestSourceDirectory>
           <violationSeverity>warning</violationSeverity>
-          <!-- TODO: remove once source fixed -->
-          <failOnViolation>false</failOnViolation>
+          <failOnViolation>true</failOnViolation>
         </configuration>
         <dependencies>
           <dependency>
diff --git a/src/main/resources/checkstyle.xml b/src/main/resources/checkstyle.xml
index 3245efd..c1e7314 100644
--- a/src/main/resources/checkstyle.xml
+++ b/src/main/resources/checkstyle.xml
@@ -118,7 +118,6 @@
     </module>
     <module name="TypecastParenPad"/>
     <module name="TypeName"/>
-    <module name="UnnecessaryParentheses"/>
     <module name="UnusedImports"/>
     <module name="UpperEll"/>
     <module name="VisibilityModifier">