diff --git a/lib_vector_search/src/grouped_finder.cpp b/lib_vector_search/src/grouped_finder.cpp
index 3b4243f..81ec7f8 100644
--- a/lib_vector_search/src/grouped_finder.cpp
+++ b/lib_vector_search/src/grouped_finder.cpp
@@ -22,7 +22,8 @@ GroupedFinder::find_prefix(std::string_view search_term) const {
   const auto word_list = group->second;
   const auto word_list_size = word_list.size();
 
-  const auto thread_count = std::thread::hardware_concurrency();
+  const auto thread_count =
+      std::min<size_t>(std::thread::hardware_concurrency(), word_list_size);
 
   forward_list<const string *> matching_words;
   mutex matching_words_mutex;