diff --git a/.idea/vcs.xml b/.idea/vcs.xml
new file mode 100644
index 0000000..35eb1dd
--- /dev/null
+++ b/.idea/vcs.xml
@@ -0,0 +1,6 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<project version="4">
+  <component name="VcsDirectoryMappings">
+    <mapping directory="" vcs="Git" />
+  </component>
+</project>
\ No newline at end of file
diff --git a/config/pmd.xml b/config/pmd.xml
new file mode 100644
index 0000000..cb0b643
--- /dev/null
+++ b/config/pmd.xml
@@ -0,0 +1,110 @@
+<?xml version="1.0"?>
+<ruleset name="erik"
+         xmlns="http://pmd.sourceforge.net/ruleset/2.0.0"
+         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+         xsi:schemaLocation="http://pmd.sourceforge.net/ruleset/2.0.0 https://pmd.sourceforge.io/ruleset_2_0_0.xsd">
+    <description>Erik's Ruleset</description>
+    <!-- BEST PRACTICES -->
+    <rule ref="category/java/bestpractices.xml">
+        <exclude name="AvoidPrintStackTrace"/>
+        <exclude name="JUnit4TestShouldUseTestAnnotation"/>
+        <exclude name="JUnitTestContainsTooManyAsserts"/>
+        <exclude name="GuardLogStatement"/>
+    </rule>
+
+    <rule ref="category/java/bestpractices.xml/MissingOverride">
+        <properties>
+            <property name="violationSuppressXPath"
+                      value="//MethodDeclaration[@Name='hashCode' or @Name='equals' or @Name='toString']"/>
+        </properties>
+    </rule>
+
+    <!-- CODE STYLE -->
+    <rule ref="category/java/codestyle.xml">
+        <exclude name="AtLeastOneConstructor"/>
+        <exclude name="ClassNamingConventions"/>
+        <exclude name="ConfusingTernary"/>
+        <exclude name="CommentDefaultAccessModifier"/>
+        <exclude name="FieldNamingConventions"/>
+        <exclude name="LocalVariableCouldBeFinal"/>
+        <exclude name="LocalVariableNamingConventions"/>
+        <exclude name="LongVariable"/>
+        <exclude name="MethodArgumentCouldBeFinal"/>
+        <exclude name="OnlyOneReturn"/>
+        <exclude name="PackageCase"/>
+        <exclude name="ShortClassName"/>
+        <exclude name="ShortMethodName"/>
+        <exclude name="ShortVariable"/>
+        <exclude name="UselessParentheses"/>
+        <exclude name="UseUnderscoresInNumericLiterals"/>
+    </rule>
+
+    <rule ref="category/java/codestyle.xml/UnnecessaryImport">
+        <properties>
+            <property name="violationSuppressRegex" value="Unused (static|.*\.\*).*"/>
+        </properties>
+    </rule>
+
+    <!-- DESIGN -->
+    <rule ref="category/java/design.xml">
+        <exclude name="AvoidCatchingGenericException"/>
+        <exclude name="AvoidDeeplyNestedIfStmts"/>
+        <exclude name="AvoidUncheckedExceptionsInSignatures"/>
+        <exclude name="CognitiveComplexity"/>
+        <exclude name="CyclomaticComplexity"/>
+        <exclude name="ExcessiveClassLength"/>
+        <exclude name="ExcessiveMethodLength"/>
+        <exclude name="ExcessiveParameterList"/>
+        <exclude name="ExcessivePublicCount"/>
+        <exclude name="GodClass"/>
+        <exclude name="LawOfDemeter"/>
+        <exclude name="LoosePackageCoupling"/>
+        <exclude name="NPathComplexity"/>
+        <exclude name="NcssCount"/>
+        <exclude name="TooManyFields"/>
+        <exclude name="TooManyMethods"/>
+        <exclude name="UseObjectForClearerAPI"/>
+    </rule>
+
+    <!-- DOCUMENTATION -->
+    <rule ref="category/java/documentation.xml">
+        <exclude name="CommentRequired"/>
+        <exclude name="CommentSize"/>
+    </rule>
+
+    <!-- ERROR PRONE -->
+    <rule ref="category/java/errorprone.xml">
+        <exclude name="AssignmentInOperand"/>
+        <exclude name="AvoidCatchingNPE"/>
+        <exclude name="AvoidDuplicateLiterals"/>
+        <exclude name="AvoidFieldNameMatchingMethodName"/>
+        <exclude name="AvoidFieldNameMatchingTypeName"/>
+        <exclude name="AvoidLiteralsInIfCondition"/>
+        <exclude name="NullAssignment"/>
+    </rule>
+
+    <rule ref="category/java/errorprone.xml/AssignmentInOperand">
+        <properties>
+            <property name="allowWhile" value="true"/>
+            <property name="allowFor" value="true"/>
+            <property name="allowIf" value="true"/>
+        </properties>
+    </rule>
+    <rule ref="category/java/errorprone.xml/AvoidDuplicateLiterals">
+        <properties>
+            <property name="skipAnnotations" value="true"/>
+        </properties>
+    </rule>
+
+    <!-- MULTITHREADING -->
+    <rule ref="category/java/multithreading.xml">
+    </rule>
+
+    <!-- PERFORMANCE -->
+    <rule ref="category/java/performance.xml">
+    </rule>
+
+    <!-- SECURITY -->
+    <rule ref="category/java/security.xml">
+    </rule>
+</ruleset>
\ No newline at end of file
diff --git a/lib/bld/bld-wrapper.properties b/lib/bld/bld-wrapper.properties
index 65caa7a..3833546 100644
--- a/lib/bld/bld-wrapper.properties
+++ b/lib/bld/bld-wrapper.properties
@@ -1,6 +1,6 @@
 bld.downloadExtensionJavadoc=false
 bld.downloadExtensionSources=true
-bld.extensions=
+bld.extension-pmd=com.uwyn.rife2:bld-pmd:0.9.4
 bld.repositories=MAVEN_CENTRAL,RIFE2_RELEASES
 bld.downloadLocation=
 bld.sourceDirectories=
diff --git a/src/bld/java/rife/bld/extension/CompileKotlinOperationBuild.java b/src/bld/java/rife/bld/extension/CompileKotlinOperationBuild.java
index 7288ec8..4766ce6 100644
--- a/src/bld/java/rife/bld/extension/CompileKotlinOperationBuild.java
+++ b/src/bld/java/rife/bld/extension/CompileKotlinOperationBuild.java
@@ -16,13 +16,12 @@
 
 package rife.bld.extension;
 
+import rife.bld.BuildCommand;
 import rife.bld.Project;
-import rife.bld.operations.RunOperation;
 import rife.bld.publish.PublishDeveloper;
 import rife.bld.publish.PublishLicense;
 import rife.bld.publish.PublishScm;
 
-import java.io.File;
 import java.util.List;
 
 import static rife.bld.dependencies.Repository.*;
@@ -78,4 +77,13 @@ public class CompileKotlinOperationBuild extends Project {
     public static void main(String[] args) {
         new CompileKotlinOperationBuild().start(args);
     }
+
+    @BuildCommand(summary = "Runs PMD analysis")
+    public void pmd() {
+        new PmdOperation()
+                .fromProject(this)
+                .failOnViolation(true)
+                .ruleSets("config/pmd.xml")
+                .execute();
+    }
 }
\ No newline at end of file
diff --git a/src/main/java/rife/bld/extension/CompileKotlinOperation.java b/src/main/java/rife/bld/extension/CompileKotlinOperation.java
index 480cb29..37e6bc1 100644
--- a/src/main/java/rife/bld/extension/CompileKotlinOperation.java
+++ b/src/main/java/rife/bld/extension/CompileKotlinOperation.java
@@ -203,6 +203,8 @@ public class CompileKotlinOperation extends AbstractOperation<CompileKotlinOpera
     /**
      * Performs the compile operation.
      */
+    @Override
+    @SuppressWarnings("PMD.SystemPrintln")
     public void execute()
             throws IOException {
         executeCreateBuildDirectories();
@@ -259,9 +261,7 @@ public class CompileKotlinOperation extends AbstractOperation<CompileKotlinOpera
         args.addAll(compileOptions());
 
         // source
-        sources.forEach(f -> {
-            args.add(f.getAbsolutePath());
-        });
+        sources.forEach(f -> args.add(f.getAbsolutePath()));
 
         if (LOGGER.isLoggable(Level.FINE) && !silent()) {
             LOGGER.fine("kotlinc " + String.join(" ", args));
@@ -292,15 +292,11 @@ public class CompileKotlinOperation extends AbstractOperation<CompileKotlinOpera
      * Part of the {@link #execute} operation, creates the build directories.
      */
     protected void executeCreateBuildDirectories() throws IOException {
-        if (buildMainDirectory() != null && !buildMainDirectory().exists()) {
-            if (!buildMainDirectory().mkdirs()) {
-                throw new IOException("Could not created build main directory: " + buildMainDirectory().getAbsolutePath());
-            }
+        if (buildMainDirectory() != null && !buildMainDirectory().exists() && !buildMainDirectory().mkdirs()) {
+            throw new IOException("Could not created build main directory: " + buildMainDirectory().getAbsolutePath());
         }
-        if (buildTestDirectory() != null && !buildTestDirectory().exists()) {
-            if (!buildTestDirectory().mkdirs()) {
-                throw new IOException("Could not created build test directory: " + buildTestDirectory().getAbsolutePath());
-            }
+        if (buildTestDirectory() != null && !buildTestDirectory().exists() && !buildTestDirectory().mkdirs()) {
+            throw new IOException("Could not created build test directory: " + buildTestDirectory().getAbsolutePath());
         }
     }
 
diff --git a/src/test/java/rife/bld/extension/CompileKotlinOperationTest.java b/src/test/java/rife/bld/extension/CompileKotlinOperationTest.java
index cfa724e..0b2ba0b 100644
--- a/src/test/java/rife/bld/extension/CompileKotlinOperationTest.java
+++ b/src/test/java/rife/bld/extension/CompileKotlinOperationTest.java
@@ -16,6 +16,7 @@
 
 package rife.bld.extension;
 
+@SuppressWarnings({"PMD.TestClassWithoutTestCases", "PMD.SystemPrintln"})
 public class CompileKotlinOperationTest {
     void verifyHello() {
         if (!"Hello World!".equals(new CompileKotlinOperation().getMessage())) {