diff --git a/src/clang_complete.cc b/src/clang_complete.cc
index 2f29a688..5bcbf1c1 100644
--- a/src/clang_complete.cc
+++ b/src/clang_complete.cc
@@ -298,7 +298,8 @@ void TryEnsureDocumentParsed(ClangCompleteManager* manager,
     args.push_back("-fspell-checking");
   }
 
-  std::vector<CXUnsavedFile> unsaved = session->working_files->AsUnsavedFiles();
+  WorkingFilesSnapshot snapshot = session->working_files->AsSnapshot();
+  std::vector<CXUnsavedFile> unsaved = snapshot.AsUnsavedFiles();
 
   LOG_S(INFO) << "Creating completion session with arguments "
               << StringJoin(args);
@@ -388,8 +389,8 @@ void CompletionQueryMain(ClangCompleteManager* completion_manager) {
     if (!session->tu)
       continue;
 
-    std::vector<CXUnsavedFile> unsaved =
-        completion_manager->working_files_->AsUnsavedFiles();
+    WorkingFilesSnapshot snapshot = completion_manager->working_files_->AsSnapshot();
+    std::vector<CXUnsavedFile> unsaved = snapshot.AsUnsavedFiles();
 
     // Emit code completion data.
     if (request->position) {
diff --git a/src/working_files.cc b/src/working_files.cc
index e88d03d4..244218cc 100644
--- a/src/working_files.cc
+++ b/src/working_files.cc
@@ -265,14 +265,6 @@ lsPosition WorkingFile::FindStableCompletionSource(
   return GetPositionForOffset(buffer_content, offset);
 }
 
-CXUnsavedFile WorkingFile::AsUnsavedFile() const {
-  CXUnsavedFile result;
-  result.Filename = filename.c_str();
-  result.Contents = buffer_content.c_str();
-  result.Length = (unsigned long)buffer_content.size();
-  return result;
-}
-
 WorkingFile* WorkingFiles::GetFileByFilename(const std::string& filename) {
   std::lock_guard<std::mutex> lock(files_mutex);
   return GetFileByFilenameNoLock(filename);
@@ -369,13 +361,27 @@ void WorkingFiles::OnClose(const lsTextDocumentItem& close) {
                  << " because it was not open";
 }
 
-std::vector<CXUnsavedFile> WorkingFiles::AsUnsavedFiles() {
-  std::lock_guard<std::mutex> lock(files_mutex);
-
+std::vector<CXUnsavedFile> WorkingFilesSnapshot::AsUnsavedFiles() const {
   std::vector<CXUnsavedFile> result;
   result.reserve(files.size());
+  for (auto& file : files) {
+    CXUnsavedFile unsaved;
+    unsaved.Filename = file.filename.c_str();
+    unsaved.Contents = file.content.c_str();
+    unsaved.Length = (unsigned long)file.content.size();
+
+    result.push_back(unsaved);
+  }
+  return result;
+}
+
+WorkingFilesSnapshot WorkingFiles::AsSnapshot() {
+  std::lock_guard<std::mutex> lock(files_mutex);
+
+  WorkingFilesSnapshot result;
+  result.files.reserve(files.size());
   for (auto& file : files)
-    result.push_back(file->AsUnsavedFile());
+    result.files.push_back({file->filename, file->buffer_content});
   return result;
 }
 
diff --git a/src/working_files.h b/src/working_files.h
index 42ec5260..9938477f 100644
--- a/src/working_files.h
+++ b/src/working_files.h
@@ -70,8 +70,15 @@ struct WorkingFile {
   lsPosition FindStableCompletionSource(lsPosition position,
                                         bool* is_global_completion,
                                         std::string* existing_completion) const;
+};
 
-  CXUnsavedFile AsUnsavedFile() const;
+struct WorkingFilesSnapshot {
+  std::vector<CXUnsavedFile> AsUnsavedFiles() const;
+  struct File {
+    std::string filename;
+    std::string content;
+  };
+  std::vector<File> files;
 };
 
 struct WorkingFiles {
@@ -94,7 +101,7 @@ struct WorkingFiles {
   void OnChange(const lsTextDocumentDidChangeParams& change);
   void OnClose(const lsTextDocumentItem& close);
 
-  std::vector<CXUnsavedFile> AsUnsavedFiles();
+  WorkingFilesSnapshot AsSnapshot();
 
   // Use unique_ptrs so we can handout WorkingFile ptrs and not have them
   // invalidated if we resize files.