diff --git a/pom.xml b/pom.xml
index b435ef6..5630b1d 100644
--- a/pom.xml
+++ b/pom.xml
@@ -163,7 +163,6 @@
                     <configLocation>${project.build.directory}/../src/test/resources/checkstyle.xml</configLocation>
                     <failOnViolation>true</failOnViolation>
                     <violationSeverity>warning</violationSeverity>
-                    <sourceDirectories>${project.build.directory}/../src/main/java</sourceDirectories>
                 </configuration>
             </plugin>
         </plugins>
diff --git a/src/main/java/edu/kit/typicalc/model/parser/LambdaLexer.java b/src/main/java/edu/kit/typicalc/model/parser/LambdaLexer.java
index 252c167..b2a6401 100644
--- a/src/main/java/edu/kit/typicalc/model/parser/LambdaLexer.java
+++ b/src/main/java/edu/kit/typicalc/model/parser/LambdaLexer.java
@@ -66,7 +66,7 @@ public class LambdaLexer {
                 return new Result<>(t);
             case '\\':
             case 'λ':
-                t = new Token(TokenType.LAMBDA, c+"", pos);
+                t = new Token(TokenType.LAMBDA, c + "", pos);
                 advance();
                 return new Result<>(t);
             default:
diff --git a/src/main/java/edu/kit/typicalc/model/parser/LambdaParser.java b/src/main/java/edu/kit/typicalc/model/parser/LambdaParser.java
index 2625ec9..e6a8924 100644
--- a/src/main/java/edu/kit/typicalc/model/parser/LambdaParser.java
+++ b/src/main/java/edu/kit/typicalc/model/parser/LambdaParser.java
@@ -27,7 +27,7 @@ public class LambdaParser {
      */
     private Token token;
 
-    private static final Set<TokenType> atomStartTokens
+    private static final Set<TokenType> ATOM_START_TOKENS
             = EnumSet.of(TokenType.VARIABLE, TokenType.NUMBER, TokenType.TRUE,
             TokenType.FALSE, TokenType.LP);
 
@@ -97,11 +97,11 @@ public class LambdaParser {
         nextToken();
         Result<VarTerm, ParseError> var = parseVar();
         if (!expect(TokenType.DOT)) {
-            // TODO
+            return new Result<>(null, ParseError.UNEXPECTED_TOKEN);
         }
         Result<LambdaTerm, ParseError> body = parseTerm();
         // TODO: Fehlerbehandlung
-        return new Result(new AbsTerm(var.unwrap(), body.unwrap()));
+        return new Result<>(new AbsTerm(var.unwrap(), body.unwrap()));
     }
 
     /**
@@ -110,7 +110,7 @@ public class LambdaParser {
      */
     private Result<LambdaTerm, ParseError> parseApplication() {
         LambdaTerm left = parseAtom().unwrap(); // TODO: Fehlerbehandlung
-        while (atomStartTokens.contains(token.getType())) {
+        while (ATOM_START_TOKENS.contains(token.getType())) {
             LambdaTerm atom = parseAtom().unwrap(); // TODO: Fehlerbehandlung
             left = new AppTerm(left, atom);
         }
diff --git a/src/main/java/edu/kit/typicalc/model/term/VarTerm.java b/src/main/java/edu/kit/typicalc/model/term/VarTerm.java
index e803363..fa67492 100644
--- a/src/main/java/edu/kit/typicalc/model/term/VarTerm.java
+++ b/src/main/java/edu/kit/typicalc/model/term/VarTerm.java
@@ -12,8 +12,12 @@ public class VarTerm extends LambdaTerm {
 
 	@Override
 	public boolean equals(Object o) {
-		if (this == o) return true;
-		if (o == null || getClass() != o.getClass()) return false;
+		if (this == o) {
+			return true;
+		}
+		if (o == null || getClass() != o.getClass()) {
+			return false;
+		}
 		VarTerm varTerm = (VarTerm) o;
 		return Objects.equals(name, varTerm.name);
 	}
diff --git a/src/main/java/edu/kit/typicalc/view/TypicalcI18NProvider.java b/src/main/java/edu/kit/typicalc/view/TypicalcI18NProvider.java
index 57b939e..adf0db2 100644
--- a/src/main/java/edu/kit/typicalc/view/TypicalcI18NProvider.java
+++ b/src/main/java/edu/kit/typicalc/view/TypicalcI18NProvider.java
@@ -12,13 +12,13 @@ import com.vaadin.flow.i18n.I18NProvider;
 
 @Component
 /**
- * Provides a simple implementation of the I18NProvider. 
+ * Provides a simple implementation of the I18NProvider.
  * Allows for multiple languages and retrieving static Strings from .property-files.
  */
 public class TypicalcI18NProvider implements I18NProvider {
-    
+
     private static final long serialVersionUID = 8261479587838699070L;
-    
+
     /**
      * Prefix of all .property-files
      */
@@ -31,12 +31,12 @@ public class TypicalcI18NProvider implements I18NProvider {
 
     @Override
     public String getTranslation(String key, Locale locale, Object... params) {
-        if(key == null) {
+        if (key == null) {
             return StringUtils.EMPTY;
         }
-        
+
         String translation;
-        
+
         try {
             final ResourceBundle bundle = ResourceBundle.getBundle(BUNDLE_PREFIX, locale);
             translation = bundle.getString(key);
@@ -44,7 +44,7 @@ public class TypicalcI18NProvider implements I18NProvider {
             throw new IllegalStateException("this should never happen:"
                     + " either an invalid locale is set or an invalid key is provided.");
         }
-        
+
         return translation;
     }
 
diff --git a/src/main/resources/application.properties b/src/main/resources/application.properties
index d579d9e..b5da9ee 100644
--- a/src/main/resources/application.properties
+++ b/src/main/resources/application.properties
@@ -2,6 +2,4 @@ server.port=${PORT:8080}
 logging.level.org.atmosphere = warn
 spring.mustache.check-template-location = false
 
-# To improve the performance during development. 
-# For more information https://vaadin.com/docs/flow/spring/tutorial-spring-configuration.html#special-configuration-parameters
 # vaadin.whitelisted-packages= org/vaadin/example
diff --git a/src/test/resources/checkstyle.xml b/src/test/resources/checkstyle.xml
index eeb91a6..3a97f7e 100644
--- a/src/test/resources/checkstyle.xml
+++ b/src/test/resources/checkstyle.xml
@@ -10,14 +10,15 @@
         <property name="tabWidth" value="4"/>
         <module name="JavadocType">
             <property name="scope" value="package"/>
-            <!-->property name="allowUndeclaredRTE" value="true"/-->
-            <!-->property name="suppressLoadErrors" value="true"/-->
+            <property name="severity" value="info"/>
         </module>
         <module name="JavadocMethod">
             <property name="scope" value="package"/>
+            <property name="severity" value="info"/>
         </module>
         <module name="JavadocVariable">
             <property name="scope" value="public"/>
+            <property name="severity" value="info"/>
         </module>
         <module name="ConstantName"/>
         <module name="LocalFinalVariableName"/>
@@ -27,7 +28,6 @@
         <module name="ParameterName"/>
         <module name="StaticVariableName"/>
         <module name="TypeName"/>
-        <module name="AvoidStarImport"/>
         <module name="IllegalImport"/>
         <module name="RedundantImport"/>
         <module name="UnusedImports"/>