diff --git a/src/sim/system.hh b/src/sim/system.hh
index d7a3b20085..c618e39444 100644
--- a/src/sim/system.hh
+++ b/src/sim/system.hh
@@ -200,7 +200,7 @@ class System : public SimObject
     std::vector<ThreadContext *> threadContexts;
     const bool multiThread;
 
-    ThreadContext *getThreadContext(ContextID tid)
+    ThreadContext *getThreadContext(ContextID tid) const
     {
         return threadContexts[tid];
     }