diff --git a/changes/unreleased.md b/changes/unreleased.md
index 3ec8407e..bf53089c 100644
--- a/changes/unreleased.md
+++ b/changes/unreleased.md
@@ -1,2 +1,3 @@
 
 - ff-158 — Improved prompts to produce less tags of better quality.
+- ff-159 — Fixed the exception in the API when no entries found.
diff --git a/ffun/ffun/api/http_handlers.py b/ffun/ffun/api/http_handlers.py
index 63c82160..d04b5d2e 100644
--- a/ffun/ffun/api/http_handlers.py
+++ b/ffun/ffun/api/http_handlers.py
@@ -73,7 +73,10 @@ async def _external_entries(  # pylint: disable=R0914
 
     tags_ids = await o_domain.get_tags_ids_for_entries(entries_ids)
 
-    whole_tags = set.union(*tags_ids.values())
+    if tags_ids:
+        whole_tags = set.union(*tags_ids.values())
+    else:
+        whole_tags = set()
 
     tags_mapping = await o_domain.get_tags_by_ids(whole_tags)