Index: lams_tool_assessment/src/java/org/lamsfoundation/lams/tool/assessment/dto/QuestionDTO.java
===================================================================
diff -u -rf5bcf9323324eb4d5add901d9e7a23c33050533a -r236d0e362fd2af8ffee9d0f447bf148063bd5497
--- lams_tool_assessment/src/java/org/lamsfoundation/lams/tool/assessment/dto/QuestionDTO.java	(.../QuestionDTO.java)	(revision f5bcf9323324eb4d5add901d9e7a23c33050533a)
+++ lams_tool_assessment/src/java/org/lamsfoundation/lams/tool/assessment/dto/QuestionDTO.java	(.../QuestionDTO.java)	(revision 236d0e362fd2af8ffee9d0f447bf148063bd5497)
@@ -1,5 +1,6 @@
 package org.lamsfoundation.lams.tool.assessment.dto;
 
+import java.util.ArrayList;
 import java.util.List;
 import java.util.Set;
 import java.util.TreeSet;
@@ -140,7 +141,6 @@
 	this.caseSensitive = qbQuestion.isCaseSensitive();
 	this.correctAnswer = qbQuestion.getCorrectAnswer();
 	this.allowRichEditor = qbQuestion.isAllowRichEditor();
-	this.units = qbQuestion.getUnits();
 	this.maxWordsLimit = qbQuestion.getMaxWordsLimit();
 	this.minWordsLimit = qbQuestion.getMinWordsLimit();
 	this.codeStyle = qbQuestion.getCodeStyle();
@@ -151,6 +151,8 @@
 	for (QbOption option : qbQuestion.getQbOptions()) {
 	    optionDtos.add(new OptionDTO(option));
 	}
+
+	this.units = new ArrayList<>(qbQuestion.getUnits());
     }
 
     @Override