diff --git a/third_party/libc++/CMakeLists.txt b/third_party/libc++/CMakeLists.txt
index f1afda159..5d768ff45 100644
--- a/third_party/libc++/CMakeLists.txt
+++ b/third_party/libc++/CMakeLists.txt
@@ -285,7 +285,7 @@ if (WIN32)
     trunk/src/support/win32/thread_win32.cpp
   )
   # hacks, override posix thread model tls implementation
-  if (MINGW)
+  if (MINGW AND MINGW_WORKAROUND)
     set(libcxx_SOURCES
       ${libcxx_SOURCES}
       emutls.cpp
diff --git a/tools/build.go b/tools/build.go
index 0945116d3..bea6f90a2 100644
--- a/tools/build.go
+++ b/tools/build.go
@@ -956,7 +956,6 @@ func buildStageGenerateBuildScript() {
 			if targetAbi == "i686" {
 				cmakeArgs = append(cmakeArgs, "-DMINGW_MSVCRT100=ON")
 			}
-			cmakeArgs = append(cmakeArgs, "-DMINGW_WORKAROUND=ON")
 			llvm_version := getLLVMVersion()
 			clang_rt_suffix := targetAbi
 			if targetAbi == "i686" {