diff --git a/DESCRIPTION b/DESCRIPTION
index c57fb6a75..46388ed6c 100644
--- a/DESCRIPTION
+++ b/DESCRIPTION
@@ -1,5 +1,5 @@
 Package: ergm
-Version: 4.6-7339
+Version: 4.6-7340
 Date: 2024-02-05
 Title: Fit, Simulate and Diagnose Exponential-Family Models for Networks
 Authors@R: c(
diff --git a/inst/include/ergm_hash_edgelist.h b/inst/include/ergm_hash_edgelist.h
index d882081d1..e11f3b18a 100644
--- a/inst/include/ergm_hash_edgelist.h
+++ b/inst/include/ergm_hash_edgelist.h
@@ -60,8 +60,12 @@ static inline void HashELGetRand(Vertex *tail, Vertex *head, HashEL *hash) {
 }
 
 static inline void HashELInsert(Vertex tail, Vertex head, HashEL *hash) {
+  kh_put_code r;
+  khiter_t pos = kh_put(DyadMapUInt, hash->hash, TH(tail, head), &r);
+  if(r == kh_put_present) return; // Already in the list.
+
   UnsrtELInsert(tail, head, hash->list);
-  kh_set(DyadMapUInt, hash->hash, TH(tail, head), hash->list->nedges);
+  kh_val(hash->hash, pos) = hash->list->nedges;
 }
 
 static inline void HashELDelete(Vertex tail, Vertex head, HashEL *hash) {