diff --git a/clang/lib/Frontend/CompilerInstance.cpp b/clang/lib/Frontend/CompilerInstance.cpp
index 366884e..2b7f183 100644
--- a/clang/lib/Frontend/CompilerInstance.cpp
+++ b/clang/lib/Frontend/CompilerInstance.cpp
@@ -170,10 +170,14 @@
   auto SerializedConsumer =
       clang::serialized_diags::create(OutputFile, DiagOpts);
 
-  assert(Diags.ownsClient());
-  Diags.setClient(new ChainedDiagnosticConsumer(
-      std::unique_ptr<DiagnosticConsumer>(Diags.takeClient()),
-      std::move(SerializedConsumer)));
+  if (Diags.ownsClient()) {
+    Diags.setClient(new ChainedDiagnosticConsumer(
+        std::unique_ptr<DiagnosticConsumer>(Diags.takeClient()),
+        std::move(SerializedConsumer)));
+  } else {
+    Diags.setClient(new ChainedDiagnosticConsumer(
+        Diags.takeClient(), std::move(SerializedConsumer)));
+  }
 }
 
 void CompilerInstance::createDiagnostics(DiagnosticConsumer *Client,