diff --git a/src/Hooks.cpp b/src/Hooks.cpp
index 496104107..a4929a07e 100644
--- a/src/Hooks.cpp
+++ b/src/Hooks.cpp
@@ -196,6 +196,7 @@ void Hooks::onExit () const
 
     // Convert to a vector of strings.
     std::vector <std::string> input;
+    input.reserve(tasks.size());
     for (auto& t : tasks)
       input.push_back (t.composeJSON ());
 
diff --git a/src/feedback.cpp b/src/feedback.cpp
index 19e6c078f..781a3eff4 100644
--- a/src/feedback.cpp
+++ b/src/feedback.cpp
@@ -47,6 +47,7 @@ static void countTasks (const std::vector <Task>&, const std::string&, int&, int
 std::string taskIdentifiers (const std::vector <Task>& tasks)
 {
   std::vector <std::string> identifiers;
+  identifiers.reserve(tasks.size());
   for (const auto& task: tasks)
     identifiers.push_back (task.identifier (true));