diff --git a/src/main/java/cz/muni/ics/kypo/training/adaptive/dto/AbstractPhaseDTO.java b/src/main/java/cz/muni/ics/kypo/training/adaptive/dto/AbstractPhaseDTO.java
index 3ec7c0e81644104e748336bc82502ba5b9381853..22ac132489334a00036d5f4f9186d891106ac6bd 100644
--- a/src/main/java/cz/muni/ics/kypo/training/adaptive/dto/AbstractPhaseDTO.java
+++ b/src/main/java/cz/muni/ics/kypo/training/adaptive/dto/AbstractPhaseDTO.java
@@ -2,9 +2,7 @@ package cz.muni.ics.kypo.training.adaptive.dto;
 
 import cz.muni.ics.kypo.training.adaptive.enums.PhaseType;
 
-import java.io.Serializable;
-
-public abstract class AbstractPhaseDTO implements Serializable {
+public abstract class AbstractPhaseDTO {
 
     private Long id;
     private String title;
diff --git a/src/main/java/cz/muni/ics/kypo/training/adaptive/dto/AbstractQuestionDTO.java b/src/main/java/cz/muni/ics/kypo/training/adaptive/dto/AbstractQuestionDTO.java
index 21fb8ddafa77840828d69c4cf24955a1876d9e3b..7b987b18ea014aa02c43cf7fa211bb473a1a593b 100644
--- a/src/main/java/cz/muni/ics/kypo/training/adaptive/dto/AbstractQuestionDTO.java
+++ b/src/main/java/cz/muni/ics/kypo/training/adaptive/dto/AbstractQuestionDTO.java
@@ -5,10 +5,9 @@ import io.swagger.annotations.ApiModelProperty;
 
 import javax.validation.constraints.NotEmpty;
 import javax.validation.constraints.NotNull;
-import java.io.Serializable;
 import java.util.List;
 
-public abstract class AbstractQuestionDTO implements Serializable {
+public abstract class AbstractQuestionDTO {
 
     @ApiModelProperty(value = "Order of question", required = true, example = "0")
     @NotNull(message = "Question order must be specified")
diff --git a/src/main/java/cz/muni/ics/kypo/training/adaptive/dto/InfoPhaseDTO.java b/src/main/java/cz/muni/ics/kypo/training/adaptive/dto/InfoPhaseDTO.java
index 39ba73b1f45b0097c0c3ee519ddb84027673cdad..e7cbcdb831f07f0c2197ce8b91889ffce7b6b787 100644
--- a/src/main/java/cz/muni/ics/kypo/training/adaptive/dto/InfoPhaseDTO.java
+++ b/src/main/java/cz/muni/ics/kypo/training/adaptive/dto/InfoPhaseDTO.java
@@ -1,8 +1,6 @@
 package cz.muni.ics.kypo.training.adaptive.dto;
 
-import java.io.Serializable;
-
-public class InfoPhaseDTO extends AbstractPhaseDTO implements Serializable {
+public class InfoPhaseDTO extends AbstractPhaseDTO {
 
     private String content;
 
diff --git a/src/main/java/cz/muni/ics/kypo/training/adaptive/dto/QuestionChoiceDTO.java b/src/main/java/cz/muni/ics/kypo/training/adaptive/dto/QuestionChoiceDTO.java
index f182228c90955b6ece21832c931e0b904e1e8f94..c4999337a8e7c41a11ece192973443c4fbe00930 100644
--- a/src/main/java/cz/muni/ics/kypo/training/adaptive/dto/QuestionChoiceDTO.java
+++ b/src/main/java/cz/muni/ics/kypo/training/adaptive/dto/QuestionChoiceDTO.java
@@ -4,9 +4,8 @@ import io.swagger.annotations.ApiModelProperty;
 
 import javax.validation.constraints.NotEmpty;
 import javax.validation.constraints.NotNull;
-import java.io.Serializable;
 
-public class QuestionChoiceDTO implements Serializable {
+public class QuestionChoiceDTO {
 
     @ApiModelProperty(value = "Question choice ID. Leave blank if new choice is added", required = true, example = "1")
     private Long id;
diff --git a/src/main/java/cz/muni/ics/kypo/training/adaptive/dto/QuestionDTO.java b/src/main/java/cz/muni/ics/kypo/training/adaptive/dto/QuestionDTO.java
index 7328f2d95eff0a83342e0a7eacdfba51f152ba6b..0b02db867a5798a01769363acf00f25ef2f3a291 100644
--- a/src/main/java/cz/muni/ics/kypo/training/adaptive/dto/QuestionDTO.java
+++ b/src/main/java/cz/muni/ics/kypo/training/adaptive/dto/QuestionDTO.java
@@ -2,9 +2,7 @@ package cz.muni.ics.kypo.training.adaptive.dto;
 
 import io.swagger.annotations.ApiModelProperty;
 
-import java.io.Serializable;
-
-public class QuestionDTO extends AbstractQuestionDTO implements Serializable {
+public class QuestionDTO extends AbstractQuestionDTO {
 
     @ApiModelProperty(value = "Question ID. Leave blank if a new question is added", required = true, example = "1")
     private Long id;
diff --git a/src/main/java/cz/muni/ics/kypo/training/adaptive/dto/TaskDTO.java b/src/main/java/cz/muni/ics/kypo/training/adaptive/dto/TaskDTO.java
index b135aa0f498bf28568d17a11448370bdcad56ac2..52575f49c15b5a34c4109c937da640d753ca35bb 100644
--- a/src/main/java/cz/muni/ics/kypo/training/adaptive/dto/TaskDTO.java
+++ b/src/main/java/cz/muni/ics/kypo/training/adaptive/dto/TaskDTO.java
@@ -1,8 +1,6 @@
 package cz.muni.ics.kypo.training.adaptive.dto;
 
-import java.io.Serializable;
-
-public class TaskDTO implements Serializable {
+public class TaskDTO {
 
     private Long id;
     private String title;