diff --git a/src/indexer.cc b/src/indexer.cc
index a16fd12c..dd3de639 100644
--- a/src/indexer.cc
+++ b/src/indexer.cc
@@ -1244,6 +1244,7 @@ Index(SemaManager *manager, WorkingFiles *wfiles, VFS *vfs,
       Clang->getDiagnostics(), Clang->getInvocation().TargetOpts));
   if (!Clang->hasTarget())
     return {};
+  Clang->getPreprocessorOpts().RetainRemappedFileBuffers = true;
 #if LLVM_VERSION_MAJOR >= 9 // rC357037
   Clang->createFileManager(FS);
 #else
@@ -1290,8 +1291,6 @@ Index(SemaManager *manager, WorkingFiles *wfiles, VFS *vfs,
     LOG_S(ERROR) << "failed to index " << main;
     return {};
   }
-  for (auto &Buf : Bufs)
-    Buf.release();
 
   std::vector<std::unique_ptr<IndexFile>> result;
   for (auto &it : param.UID2File) {
diff --git a/src/sema_manager.cc b/src/sema_manager.cc
index 8ebdca0a..9ee160bf 100644
--- a/src/sema_manager.cc
+++ b/src/sema_manager.cc
@@ -301,6 +301,7 @@ std::unique_ptr<CompilerInstance> BuildCompilerInstance(
       Clang->getDiagnostics(), Clang->getInvocation().TargetOpts));
   if (!Clang->hasTarget())
     return nullptr;
+  Clang->getPreprocessorOpts().RetainRemappedFileBuffers = true;
   // Construct SourceManager with UserFilesAreVolatile: true because otherwise
   // RequiresNullTerminator: true may cause out-of-bounds read when a file is
   // mmap'ed but is saved concurrently.
@@ -482,7 +483,6 @@ void *CompletionMain(void *manager_) {
     Clang->setCodeCompletionConsumer(task->Consumer.release());
     if (!Parse(*Clang))
       continue;
-    Buf.release();
 
     task->on_complete(&Clang->getCodeCompletionConsumer());
   }
@@ -572,7 +572,6 @@ void *DiagnosticMain(void *manager_) {
       continue;
     if (!Parse(*Clang))
       continue;
-    Buf.release();
 
     auto Fill = [](const DiagBase &d, Diagnostic &ret) {
       ret.range = lsRange{{d.range.start.line, d.range.start.column},