diff --git a/ui/scripts/cloud.core.diskoffering.js b/ui/scripts/cloud.core.diskoffering.js
index a9a4ea12e5b..528e5fc5d44 100644
--- a/ui/scripts/cloud.core.diskoffering.js
+++ b/ui/scripts/cloud.core.diskoffering.js
@@ -41,7 +41,7 @@ function afterLoadDiskOfferingJSP() {
 				var isValid = true;					
 				isValid &= validateString("Name", thisDialog.find("#add_disk_name"), thisDialog.find("#add_disk_name_errormsg"));
 				isValid &= validateString("Description", thisDialog.find("#add_disk_description"), thisDialog.find("#add_disk_description_errormsg"));
-				//isValid &= validateNumber("Disk size", thisDialog.find("#add_disk_disksize"), thisDialog.find("#add_disk_disksize_errormsg"), 0, null); 
+				isValid &= validateNumber("Disk size", thisDialog.find("#add_disk_disksize"), thisDialog.find("#add_disk_disksize_errormsg"), 0, null, true); //optional
 				isValid &= validateString("Tags", thisDialog.find("#add_disk_tags"), thisDialog.find("#add_disk_tags_errormsg"), true);	//optional	
 				if (!isValid) 
 				    return;