diff --git a/src/protocol/AcknowledgeManager.cpp b/src/protocol/AcknowledgeManager.cpp
index b2ee670..6d5484c 100644
--- a/src/protocol/AcknowledgeManager.cpp
+++ b/src/protocol/AcknowledgeManager.cpp
@@ -101,7 +101,7 @@ ssize_t AcknowledgeManager::execute_resend(const system_clock::time_point& now ,
     {
         bool cleanup{false};
         std::lock_guard lock{this->entry_lock};
-        need_resend.resize(this->entries.size());
+        need_resend.reserve(this->entries.size());
 
         for (auto &entry : this->entries) {
             if(entry->acknowledged) {