diff --git a/libphobos/libdruntime/core/thread.d b/libphobos/libdruntime/core/thread.d
index ff15d066a49..98a81425f47 100644
--- a/libphobos/libdruntime/core/thread.d
+++ b/libphobos/libdruntime/core/thread.d
@@ -1547,7 +1547,7 @@ private:
 
     version (Solaris)
     {
-        __gshared immutable bool m_isRTClass;
+        __gshared bool m_isRTClass;
     }
 
 private: