diff --git a/aos/events/logging/logfile_sorting.cc b/aos/events/logging/logfile_sorting.cc
index 3f637f8..eedfa62 100644
--- a/aos/events/logging/logfile_sorting.cc
+++ b/aos/events/logging/logfile_sorting.cc
@@ -1238,8 +1238,15 @@
                   return a.second < b.second;
                 });
       new_parts.parts.reserve(parts.second.parts.size());
-      for (std::pair<std::string, int> &p : parts.second.parts) {
-        new_parts.parts.emplace_back(std::move(p.first));
+      {
+        int last_parts_index = -1;
+        for (std::pair<std::string, int> &p : parts.second.parts) {
+          CHECK_LT(last_parts_index, p.second)
+              << ": Found duplicate parts in '" << new_parts.parts.back()
+              << "' and '" << p.first << "'";
+          last_parts_index = p.second;
+          new_parts.parts.emplace_back(std::move(p.first));
+        }
       }
 
       CHECK(!parts.second.config_sha256.empty());
diff --git a/aos/events/logging/logger_test.cc b/aos/events/logging/logger_test.cc
index 226c084..8d8a2a6 100644
--- a/aos/events/logging/logger_test.cc
+++ b/aos/events/logging/logger_test.cc
@@ -2501,6 +2501,30 @@
   ConfirmReadable(pi1_single_direction_logfiles_);
 }
 
+// Tests that we explode if someone passes in a part file twice with a better
+// error than an out of order error.
+TEST_P(MultinodeLoggerTest, DuplicateLogFiles) {
+  time_converter_.AddMonotonic(
+      {BootTimestamp::epoch(),
+       BootTimestamp::epoch() + chrono::seconds(1000)});
+  {
+    LoggerState pi1_logger = MakeLogger(pi1_);
+
+    event_loop_factory_.RunFor(chrono::milliseconds(95));
+
+    StartLogger(&pi1_logger);
+
+    event_loop_factory_.RunFor(chrono::milliseconds(10000));
+  }
+
+  std::vector<std::string> duplicates;
+  for (const std::string &f : pi1_single_direction_logfiles_) {
+    duplicates.emplace_back(f);
+    duplicates.emplace_back(f);
+  }
+  EXPECT_DEATH({ SortParts(duplicates); }, "Found duplicate parts in");
+}
+
 // Tests that we properly handle a dead node.  Do this by just disconnecting it
 // and only using one nodes of logs.
 TEST_P(MultinodeLoggerTest, DeadNode) {