diff --git a/lib/BasicsC/operating-system.h b/lib/BasicsC/operating-system.h
index 6eeed2deb3..6c46a578e6 100644
--- a/lib/BasicsC/operating-system.h
+++ b/lib/BasicsC/operating-system.h
@@ -132,6 +132,10 @@
 #define TRI_HAVE_GETLINE                    1
 #endif
 
+#if __llvm__ == 1
+#define thread_local __thread
+#endif
+
 ////////////////////////////////////////////////////////////////////////////////
 /// @brief alignment and limits
 ////////////////////////////////////////////////////////////////////////////////