diff --git a/application/cmdbabstract.class.inc.php b/application/cmdbabstract.class.inc.php
index 316753c6b..5f61bb0e2 100644
--- a/application/cmdbabstract.class.inc.php
+++ b/application/cmdbabstract.class.inc.php
@@ -1938,7 +1938,16 @@ EOF
 					$sHidden = "<input type=\"hidden\" id=\"{$iId}_count\" value=\"$iEntriesCount\"/>"; // To know how many entries the case log already contains
 
 					$sHTMLValue = "<div class=\"field_input_zone field_input_caselog caselog\" $sStyle>$sHeader<textarea class=\"htmlEditor\" style=\"border:0;width:100%\" title=\"$sHelpText\" name=\"attr_{$sFieldPrefix}{$sAttCode}{$sNameSuffix}\" rows=\"8\" cols=\"40\" id=\"$iId\">".htmlentities($sEditValue, ENT_QUOTES, 'UTF-8')."</textarea>$sPreviousLog</div>{$sValidationSpan}{$sReloadSpan}$sHidden";
-					$oPage->add_ready_script("$('#$iId').bind('keyup change validate', function(evt, sFormId) { return ValidateCaseLogField('$iId', $bMandatory, sFormId) } );"); // Custom validation function
+
+					// Note: This should be refactored for all types of attribute (see at the end of this function) but as we are doing this for a maintenance release, we are scheduling it for the next main release in to order to avoid regressions as much as possible.
+					$sNullValue = $oAttDef->GetNullValue();
+					if (!is_numeric($sNullValue))
+					{
+						$sNullValue = "'$sNullValue'"; // Add quotes to turn this into a JS string if it's not a number
+					}
+					$sOriginalValue = ($iFlags & OPT_ATT_MUSTCHANGE) ? json_encode($value->GetModifiedEntry('html')) : 'undefined';
+
+					$oPage->add_ready_script("$('#$iId').bind('keyup change validate', function(evt, sFormId) { return ValidateCaseLogField('$iId', $bMandatory, sFormId, $sNullValue, $sOriginalValue) } );"); // Custom validation function
 
 					// Replace the text area with CKEditor
 					// To change the default settings of the editor,
diff --git a/js/forms-json-utils.js b/js/forms-json-utils.js
index 9eb54a9e7..f00e37385 100644
--- a/js/forms-json-utils.js
+++ b/js/forms-json-utils.js
@@ -297,6 +297,7 @@ function ValidateCKEditField(sFieldId, sPattern, bMandatory, sFormId, nullValue,
 			}
 			else
 			{
+				// Note: value change check is not working well yet as the HTML to Text conversion is not exactly the same when done from the PHP value or the CKEditor value.
 				sExplain = Dict.S('UI:ValueMustBeChanged');
 			}
 		}
@@ -308,6 +309,7 @@ function ValidateCKEditField(sFieldId, sPattern, bMandatory, sFormId, nullValue,
 
 	ReportFieldValidationStatus(sFieldId, sFormId, bValid, sExplain);
 
+	// We need to check periodically as CKEditor doesn't trigger our events. More details in UIHTMLEditorWidget::Display() @ line 92
 	setTimeout(function(){ValidateCKEditField(sFieldId, sPattern, bMandatory, sFormId, nullValue, originalValue);}, 500);
 }
 
@@ -374,32 +376,39 @@ function ValidatePasswordField(id, sFormId)
 
 //Special validation function for case log fields, taking into account the history
 // to determine if the field is empty or not
-function ValidateCaseLogField(sFieldId, bMandatory, sFormId)
+function ValidateCaseLogField(sFieldId, bMandatory, sFormId, nullValue, originalValue)
 {
-	bValid = true;
+	var bValid = true;
+	var sExplain = '';
+	var sTextContent;
 	
 	if ($('#'+sFieldId).attr('disabled'))
 	{
 		bValid = true; // disabled fields are not checked
 	}
-	else if (!bMandatory)
-	{
-		bValid = true;
-	}
 	else
 	{
-		if (bMandatory)
+		// Get the contents (with tags)
+		// Note: For CaseLog we can't retrieve the formatted contents from CKEditor (unlike in ValidateCKEditorField() method) because of the place holder.
+		sTextContent = $('#' + sFieldId).val();
+		var count = $('#'+sFieldId+'_count').val();
+
+		if (bMandatory && (count == 0) && (sTextContent == nullValue))
 		{
-			var count = $('#'+sFieldId+'_count').val();
-			if ( (count == 0) && ($('#'+sFieldId).val() == '') )
-			{
-				// No previous entry and no content typed
-				bValid = false;
-			}
+			// No previous entry and no content typed
+			bValid = false;
+			sExplain = Dict.S('UI:ValueMustBeSet');
+		}
+		else if ((originalValue != undefined) && (sTextContent == originalValue))
+		{
+			bValid = false;
+			sExplain = Dict.S('UI:ValueMustBeChanged');
 		}
 	}
-	ReportFieldValidationStatus(sFieldId, sFormId, bValid, '');
-	return bValid;
+	ReportFieldValidationStatus(sFieldId, sFormId, bValid, '' /* sExplain */);
+
+	// We need to check periodically as CKEditor doesn't trigger our events. More details in UIHTMLEditorWidget::Display() @ line 92
+	setTimeout(function(){ValidateCaseLogField(sFieldId, bMandatory, sFormId, nullValue, originalValue);}, 500);
 }
 
 // Validate the inputs depending on the current setting