diff --git a/pom.xml b/pom.xml
index 2637511..14ae66a 100755
--- a/pom.xml
+++ b/pom.xml
@@ -108,6 +108,16 @@
 		<defaultGoal>package</defaultGoal>
 	</build>
 	<dependencies>
+		<dependency>
+			<groupId>com.google.guava</groupId>
+			<artifactId>guava</artifactId>
+			<version>27.0-jre</version>
+		</dependency>
+		<dependency>
+			<groupId>commons-io</groupId>
+			<artifactId>commons-io</artifactId>
+			<version>2.5</version>
+		</dependency>
 		<dependency>
 			<groupId>org.antlr</groupId>
 			<artifactId>antlr4</artifactId>
@@ -123,24 +133,12 @@
 			<artifactId>antlr4-maven-plugin</artifactId>
 			<version>${antlr.version}</version>
 		</dependency>
-
 		<dependency>
 			<groupId>org.slf4j</groupId>
 			<artifactId>slf4j-api</artifactId>
 			<version>1.7.25</version>
 		</dependency>
 
-		<dependency>
-			<groupId>commons-io</groupId>
-			<artifactId>commons-io</artifactId>
-			<version>2.5</version>
-		</dependency>
-		<dependency>
-			<groupId>org.apache.commons</groupId>
-			<artifactId>commons-lang3</artifactId>
-			<version>3.5</version>
-		</dependency>
-
 		<dependency>
 			<groupId>junit</groupId>
 			<artifactId>junit</artifactId>
diff --git a/src/main/java/io/proleap/vb6/asg/metamodel/impl/ScopedElementImpl.java b/src/main/java/io/proleap/vb6/asg/metamodel/impl/ScopedElementImpl.java
index e2f8d8c..b99956b 100755
--- a/src/main/java/io/proleap/vb6/asg/metamodel/impl/ScopedElementImpl.java
+++ b/src/main/java/io/proleap/vb6/asg/metamodel/impl/ScopedElementImpl.java
@@ -9,7 +9,8 @@
 package io.proleap.vb6.asg.metamodel.impl;
 
 import org.antlr.v4.runtime.ParserRuleContext;
-import org.apache.commons.lang3.StringUtils;
+
+import com.google.common.base.Strings;
 
 import io.proleap.vb6.asg.metamodel.Module;
 import io.proleap.vb6.asg.metamodel.Program;
@@ -59,6 +60,6 @@ public abstract class ScopedElementImpl extends ASGElementImpl implements Scoped
 	}
 
 	protected String getSymbol(final String name) {
-		return StringUtils.isBlank(name) ? name : name.toLowerCase();
+		return Strings.isNullOrEmpty(name) ? name : name.toLowerCase();
 	}
 }
diff --git a/src/main/java/io/proleap/vb6/asg/runner/impl/VbParserRunnerImpl.java b/src/main/java/io/proleap/vb6/asg/runner/impl/VbParserRunnerImpl.java
index 6425426..a976c61 100755
--- a/src/main/java/io/proleap/vb6/asg/runner/impl/VbParserRunnerImpl.java
+++ b/src/main/java/io/proleap/vb6/asg/runner/impl/VbParserRunnerImpl.java
@@ -21,7 +21,6 @@ import org.antlr.v4.runtime.CharStreams;
 import org.antlr.v4.runtime.CommonTokenStream;
 import org.apache.commons.io.FileUtils;
 import org.apache.commons.io.FilenameUtils;
-import org.apache.commons.lang3.StringUtils;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
@@ -162,13 +161,17 @@ public class VbParserRunnerImpl implements VbParserRunner {
 		}
 	}
 
+	protected String capitalize(final String line) {
+		return Character.toUpperCase(line.charAt(0)) + line.substring(1);
+	}
+
 	protected VbParserParams createDefaultParams() {
 		final VbParserParams result = new VbParserParamsImpl();
 		return result;
 	}
 
 	protected String getModuleName(final File inputFile) {
-		return StringUtils.capitalize(FilenameUtils.removeExtension(inputFile.getName()));
+		return capitalize(FilenameUtils.removeExtension(inputFile.getName()));
 	}
 
 	protected boolean isClazzModule(final File inputFile) {
diff --git a/src/test/java/io/proleap/vb6/TestGenerator.java b/src/test/java/io/proleap/vb6/TestGenerator.java
index a595ba3..d4f6120 100755
--- a/src/test/java/io/proleap/vb6/TestGenerator.java
+++ b/src/test/java/io/proleap/vb6/TestGenerator.java
@@ -19,10 +19,11 @@ import java.util.Arrays;
 import org.antlr.v4.runtime.ANTLRInputStream;
 import org.antlr.v4.runtime.CommonTokenStream;
 import org.apache.commons.io.FilenameUtils;
-import org.apache.commons.lang3.StringUtils;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
+import com.google.common.base.Strings;
+
 import io.proleap.vb6.VisualBasic6Parser.StartRuleContext;
 import io.proleap.vb6.util.TreeUtils;
 
@@ -110,7 +111,7 @@ public class TestGenerator {
 						subOutputDirectory.mkdirs();
 
 						// determine the package name of test classes
-						final String subPackageName = StringUtils.isBlank(packageName) ? subInputDirectoryName
+						final String subPackageName = Strings.isNullOrEmpty(packageName) ? subInputDirectoryName
 								: packageName + "." + subInputDirectoryName;
 
 						generateTestClasses(subInputDirectory, subOutputDirectory, subPackageName);
diff --git a/src/test/java/io/proleap/vb6/runner/impl/VbParseTestRunnerImpl.java b/src/test/java/io/proleap/vb6/runner/impl/VbParseTestRunnerImpl.java
index ee603b2..b0285ee 100644
--- a/src/test/java/io/proleap/vb6/runner/impl/VbParseTestRunnerImpl.java
+++ b/src/test/java/io/proleap/vb6/runner/impl/VbParseTestRunnerImpl.java
@@ -21,10 +21,11 @@ import org.antlr.v4.runtime.CommonTokenStream;
 import org.antlr.v4.runtime.tree.Trees;
 import org.apache.commons.io.FileUtils;
 import org.apache.commons.io.FilenameUtils;
-import org.apache.commons.lang3.StringUtils;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
+import com.google.common.base.Strings;
+
 import io.proleap.vb6.VisualBasic6Lexer;
 import io.proleap.vb6.VisualBasic6Parser;
 import io.proleap.vb6.VisualBasic6Parser.StartRuleContext;
@@ -57,7 +58,7 @@ public class VbParseTestRunnerImpl implements VbParseTestRunner {
 
 		final String treeFileData = FileUtils.readFileToString(treeFile);
 
-		if (!StringUtils.isBlank(treeFileData)) {
+		if (!Strings.isNullOrEmpty(treeFileData)) {
 			LOG.info("Comparing parse tree with file {}.", treeFile.getName());
 
 			final String inputFileTree = Trees.toStringTree(startRule, parser);
diff --git a/src/test/java/io/proleap/vb6/util/TreeUtils.java b/src/test/java/io/proleap/vb6/util/TreeUtils.java
index ff2aa43..a8cf6cf 100644
--- a/src/test/java/io/proleap/vb6/util/TreeUtils.java
+++ b/src/test/java/io/proleap/vb6/util/TreeUtils.java
@@ -9,6 +9,8 @@ import org.antlr.v4.runtime.tree.Tree;
 import org.antlr.v4.runtime.tree.Trees;
 import org.sonatype.inject.Nullable;
 
+import com.google.common.base.Strings;
+
 public class TreeUtils {
 
 	public static final String NEWLINE = "\n";
@@ -16,7 +18,7 @@ public class TreeUtils {
 	public static final String TAB = "\t";
 
 	public static String indent(final int indent) {
-		return org.apache.commons.lang3.StringUtils.repeat(TAB, indent);
+		return Strings.repeat(TAB, indent);
 	}
 
 	/**