diff --git a/GirafEntities/WeekPlanner/DTOs/PictogramDTO.cs b/GirafEntities/WeekPlanner/DTOs/PictogramDTO.cs
index c6a07082..3fc4e91e 100644
--- a/GirafEntities/WeekPlanner/DTOs/PictogramDTO.cs
+++ b/GirafEntities/WeekPlanner/DTOs/PictogramDTO.cs
@@ -31,7 +31,7 @@ public class PictogramDTO
         /// <summary>
         /// Hash of DTO
         /// </summary>
-        public string ImageHash { get; set; }
+        public string? ImageHash { get; set; }
 
         /// <summary>
         /// Generated image URL