diff --git a/jsprit-core/src/main/java/jsprit/core/problem/Skills.java b/jsprit-core/src/main/java/jsprit/core/problem/Skills.java
index 36142574..fcee453c 100644
--- a/jsprit-core/src/main/java/jsprit/core/problem/Skills.java
+++ b/jsprit-core/src/main/java/jsprit/core/problem/Skills.java
@@ -58,7 +58,7 @@ public class Skills {
          * @return builder
          */
         public Builder addAllSkills(Collection<String> skills){
-            for(String skill : skills) this.skills.add(skill);
+            for(String skill : skills) addSkill(skill);
             return this;
         }
 
diff --git a/jsprit-core/src/test/java/jsprit/core/problem/SkillsTest.java b/jsprit-core/src/test/java/jsprit/core/problem/SkillsTest.java
index 38628a8f..88f87d5f 100644
--- a/jsprit-core/src/test/java/jsprit/core/problem/SkillsTest.java
+++ b/jsprit-core/src/test/java/jsprit/core/problem/SkillsTest.java
@@ -26,6 +26,13 @@ public class SkillsTest {
         assertTrue(skills.containsSkill("skIll2"));
     }
 
+    @Test
+    public void whenSkillsAddedCaseInsensitive2_theyShouldBeinSkillSet(){
+        Skills skills = Skills.Builder.newInstance().addSkill("Skill1").addSkill("skill2").build();
+        assertTrue(skills.containsSkill("skilL1"));
+        assertTrue(skills.containsSkill("skIll2"));
+    }
+
     @Test
     public void whenSkillsAddedThroughAddAll_theyShouldBeinSkillSet(){
         Set<String> skillSet = new HashSet<String>();
@@ -36,4 +43,24 @@ public class SkillsTest {
         assertTrue(skills.containsSkill("skill2"));
     }
 
+    @Test
+    public void whenSkillsAddedThroughAddAllCaseInsensitive_theyShouldBeinSkillSet(){
+        Set<String> skillSet = new HashSet<String>();
+        skillSet.add("skill1");
+        skillSet.add("skill2");
+        Skills skills = Skills.Builder.newInstance().addAllSkills(skillSet).build();
+        assertTrue(skills.containsSkill("skilL1"));
+        assertTrue(skills.containsSkill("skill2"));
+    }
+
+    @Test
+    public void whenSkillsAddedThroughAddAllCaseInsensitive2_theyShouldBeinSkillSet(){
+        Set<String> skillSet = new HashSet<String>();
+        skillSet.add("skill1");
+        skillSet.add("Skill2");
+        Skills skills = Skills.Builder.newInstance().addAllSkills(skillSet).build();
+        assertTrue(skills.containsSkill("skill1"));
+        assertTrue(skills.containsSkill("skill2"));
+    }
+
 }