diff --git a/src/tools/clangrefactoringbackend/source/refactoringserver.cpp b/src/tools/clangrefactoringbackend/source/refactoringserver.cpp
index f4e5372e9a5..996d82e5616 100644
--- a/src/tools/clangrefactoringbackend/source/refactoringserver.cpp
+++ b/src/tools/clangrefactoringbackend/source/refactoringserver.cpp
@@ -125,7 +125,11 @@ void RefactoringServer::gatherSourceRangesAndDiagnosticsForQueryMessage(
 {
     std::vector<Future> futures;
 
+#ifdef _WIN32
+    std::size_t freeProcessors = 1;
+#else
     std::size_t freeProcessors = std::thread::hardware_concurrency();
+#endif
 
     while (!sources.empty() || !futures.empty()) {
         --freeProcessors;