diff --git a/src/main/java/org/springframework/data/repository/util/QueryExecutionConverters.java b/src/main/java/org/springframework/data/repository/util/QueryExecutionConverters.java
index 00a0968b9..fd982aa91 100644
--- a/src/main/java/org/springframework/data/repository/util/QueryExecutionConverters.java
+++ b/src/main/java/org/springframework/data/repository/util/QueryExecutionConverters.java
@@ -567,7 +567,7 @@ public abstract class QueryExecutionConverters {
 	 * @author Oliver Gierke
 	 * @since 1.12
 	 */
-	private static enum GuavaOptionalUnwrapper implements Converter<Object, Object> {
+	private enum GuavaOptionalUnwrapper implements Converter<Object, Object> {
 
 		INSTANCE;
 
@@ -587,7 +587,7 @@ public abstract class QueryExecutionConverters {
 	 * @author Oliver Gierke
 	 * @since 1.12
 	 */
-	private static enum Jdk8OptionalUnwrapper implements Converter<Object, Object> {
+	private enum Jdk8OptionalUnwrapper implements Converter<Object, Object> {
 
 		INSTANCE;
 
@@ -608,7 +608,7 @@ public abstract class QueryExecutionConverters {
 	 * @author Mark Paluch
 	 * @since 1.12
 	 */
-	private static enum ScalOptionUnwrapper implements Converter<Object, Object> {
+	private enum ScalOptionUnwrapper implements Converter<Object, Object> {
 
 		INSTANCE;
 
@@ -640,7 +640,7 @@ public abstract class QueryExecutionConverters {
 	 * @author Oliver Gierke
 	 * @since 1.13
 	 */
-	private static enum JavaslangOptionUnwrapper implements Converter<Object, Object> {
+	private enum JavaslangOptionUnwrapper implements Converter<Object, Object> {
 
 		INSTANCE;
 
@@ -681,7 +681,7 @@ public abstract class QueryExecutionConverters {
 	 * @author Oliver Gierke
 	 * @since 2.0
 	 */
-	private static enum VavrOptionUnwrapper implements Converter<Object, Object> {
+	private enum VavrOptionUnwrapper implements Converter<Object, Object> {
 
 		INSTANCE;