diff --git a/compaction/compaction.cc b/compaction/compaction.cc
index 7cc00e00aa..dc0ac7e583 100644
--- a/compaction/compaction.cc
+++ b/compaction/compaction.cc
@@ -414,9 +414,12 @@ private:
 
 class formatted_sstables_list {
     bool _include_origin = true;
-    std::vector<sstring> _ssts;
+    std::vector<std::string> _ssts;
 public:
     formatted_sstables_list() = default;
+    void reserve(size_t n) {
+        _ssts.reserve(n);
+    }
     explicit formatted_sstables_list(const std::vector<shared_sstable>& ssts, bool include_origin) : _include_origin(include_origin) {
         _ssts.reserve(ssts.size());
         for (const auto& sst : ssts) {
@@ -435,9 +438,7 @@ public:
 };
 
 std::ostream& operator<<(std::ostream& os, const formatted_sstables_list& lst) {
-    os << "[";
-    os << boost::algorithm::join(lst._ssts, ",");
-    os << "]";
+    fmt::print(os, "[{}]", fmt::join(lst._ssts, ","));
     return os;
 }
 
@@ -641,6 +642,7 @@ private:
     future<> setup() {
         auto ssts = make_lw_shared<sstables::sstable_set>(make_sstable_set_for_input());
         formatted_sstables_list formatted_msg;
+        formatted_msg.reserve(_sstables.size());
         auto fully_expired = _table_s.fully_expired_sstables(_sstables, gc_clock::now());
         min_max_tracker<api::timestamp_type> timestamp_tracker;