diff --git a/bacnet-stack/bacstr.c b/bacnet-stack/bacstr.c
index 513f8cf0..106b6dfe 100644
--- a/bacnet-stack/bacstr.c
+++ b/bacnet-stack/bacstr.c
@@ -257,6 +257,16 @@ bool characterstring_same(
       }
     }
   }
+  else if (src)
+  {
+    if (src->length == 0)
+      same_status = true;
+  }
+  else if (dest)
+  {
+    if (dest->length == 0)
+      same_status = true;
+  }
 
   return same_status;
 }