diff --git a/swh/storage/postgresql/storage.py b/swh/storage/postgresql/storage.py
--- a/swh/storage/postgresql/storage.py
+++ b/swh/storage/postgresql/storage.py
@@ -107,7 +107,7 @@
 class Storage:
     """SWH storage datastore proxy, encompassing DB and object storage"""
 
-    current_version: int = 183
+    current_version: int = 184
 
     def __init__(
         self,
diff --git a/swh/storage/sql/40-funcs.sql b/swh/storage/sql/40-funcs.sql
--- a/swh/storage/sql/40-funcs.sql
+++ b/swh/storage/sql/40-funcs.sql
@@ -658,9 +658,16 @@
     from origin
     where url = origin_url
   ), last_known_visit as (
-    select coalesce(max(visit), 0) as visit
-    from origin_visit
-    where origin = (select id from origin_id)
+    select coalesce(
+      (
+        select visit
+        from origin_visit
+        where origin = (select id from origin_id)
+        order by visit desc
+        limit 1
+        for update
+      ),
+    0) as visit
   )
   insert into origin_visit (origin, date, type, visit)
   values ((select id from origin_id), date, type,
diff --git a/swh/storage/sql/upgrades/184.sql b/swh/storage/sql/upgrades/184.sql
new file mode 100644
--- /dev/null
+++ b/swh/storage/sql/upgrades/184.sql
@@ -0,0 +1,33 @@
+-- SWH DB schema upgrade
+-- from_version: 183
+-- to_version: 184
+-- description: origin_visit_add: Fix crash when adding multiple visits to the same origin simultaneously
+
+insert into dbversion(version, release, description)
+    values(184, now(), 'Work In Progress');
+
+create or replace function swh_origin_visit_add(origin_url text, date timestamptz, type text)
+    returns bigint
+    language sql
+as $$
+  with origin_id as (
+    select id
+    from origin
+    where url = origin_url
+  ), last_known_visit as (
+    select coalesce(
+      (
+        select visit
+        from origin_visit
+        where origin = (select id from origin_id)
+        order by visit desc
+        limit 1
+        for update
+      ),
+    0) as visit
+  )
+  insert into origin_visit (origin, date, type, visit)
+  values ((select id from origin_id), date, type,
+          (select visit from last_known_visit) + 1)
+  returning visit;
+$$;