diff --git a/README.md b/README.md
index 503d75c2..9bcb6775 100644
--- a/README.md
+++ b/README.md
@@ -317,7 +317,8 @@ To run test **with** updates (from `build` directory)
 - Visual search engine for 1M amazon products (MXNet + HNSW): [website](https://thomasdelteil.github.io/VisualSearch_MXNet/), [code](https://github.com/ThomasDelteil/VisualSearch_MXNet), demo by [@ThomasDelteil](https://github.com/ThomasDelteil)
 
 ### References
-
+HNSW paper:
+```
 @article{malkov2018efficient,
   title={Efficient and robust approximate nearest neighbor search using hierarchical navigable small world graphs},
   author={Malkov, Yu A and Yashunin, Dmitry A},
@@ -328,3 +329,6 @@ To run test **with** updates (from `build` directory)
   year={2018},
   publisher={IEEE}
 }
+```
+
+The update algorithm supported in this repository is to be published in "Dynamic Updates For HNSW, Hierarchical Navigable Small World Graphs" US Patent 15/929,802 by Apoorv Sharma, Abhishek Tayal and Yury Malkov.
diff --git a/hnswlib/bruteforce.h b/hnswlib/bruteforce.h
index 24260400..6074c5f9 100644
--- a/hnswlib/bruteforce.h
+++ b/hnswlib/bruteforce.h
@@ -78,7 +78,8 @@ namespace hnswlib {
             dict_external_to_internal.erase(cur_external);
 
             labeltype label=*((labeltype*)(data_ + size_per_element_ * (cur_element_count-1) + data_size_));
-            dict_external_to_internal[label]=cur_c;
+            if (cur_external != label)
+                dict_external_to_internal[label]=cur_c;
             memcpy(data_ + size_per_element_ * cur_c,
                    data_ + size_per_element_ * (cur_element_count-1),
                    data_size_+sizeof(labeltype));