diff --git a/compaction/compaction_strategy.cc b/compaction/compaction_strategy.cc
index 4cd1c28b7d..9206c6db75 100644
--- a/compaction/compaction_strategy.cc
+++ b/compaction/compaction_strategy.cc
@@ -12,6 +12,7 @@
 #include <vector>
 #include <chrono>
 #include <seastar/core/shared_ptr.hh>
+#include "seastar/core/on_internal_error.hh"
 #include "sstables/shared_sstable.hh"
 #include "sstables/sstables.hh"
 #include "compaction.hh"
@@ -283,24 +284,25 @@ public:
         return b;
     }
 
-    // FIXME: Should provide strong exception safety guarantees
+    // Provides strong exception safety guarantees
     virtual void replace_sstables(const std::vector<sstables::shared_sstable>& old_ssts, const std::vector<sstables::shared_sstable>& new_ssts) override {
         struct replacement {
             std::vector<sstables::shared_sstable> old_ssts;
             std::vector<sstables::shared_sstable> new_ssts;
         };
         std::unordered_map<api::timestamp_type, replacement> per_window_replacement;
+        auto tmp_windows = _windows;
 
         for (auto& sst : new_ssts) {
             auto bound = lower_bound_of(sst->get_stats_metadata().max_timestamp);
-            if (!_windows.contains(bound)) {
-                _windows.emplace(bound, size_tiered_backlog_tracker(_stcs_options));
+            if (!tmp_windows.contains(bound)) {
+                tmp_windows.emplace(bound, size_tiered_backlog_tracker(_stcs_options));
             }
             per_window_replacement[bound].new_ssts.push_back(std::move(sst));
         }
         for (auto& sst : old_ssts) {
             auto bound = lower_bound_of(sst->get_stats_metadata().max_timestamp);
-            if (_windows.contains(bound)) {
+            if (tmp_windows.contains(bound)) {
                 per_window_replacement[bound].old_ssts.push_back(std::move(sst));
             }
         }
@@ -308,12 +310,20 @@ public:
         for (auto& [bound, r] : per_window_replacement) {
             // All windows must exist here, as windows are created for new files and will
             // remain alive as long as there's a single file in them
-            auto& w = _windows.at(bound);
-            w.replace_sstables(std::move(r.old_ssts), std::move(r.new_ssts));
+            auto it = tmp_windows.find(bound);
+            if (it == tmp_windows.end()) {
+                on_internal_error(clogger, fmt::format("window for bound {} not found", bound));
+            }
+            auto& w = it->second;
+            w.replace_sstables(r.old_ssts, r.new_ssts);
             if (w.total_bytes() <= 0) {
-                _windows.erase(bound);
+                tmp_windows.erase(bound);
             }
         }
+
+        std::invoke([&] () noexcept {
+            _windows = std::move(tmp_windows);
+        });
     }
 };