diff --git a/src/sim/sim_object.hh b/src/sim/sim_object.hh
index ec565ce82b..00bb3fee61 100644
--- a/src/sim/sim_object.hh
+++ b/src/sim/sim_object.hh
@@ -36,10 +36,11 @@
 #ifndef __SIM_OBJECT_HH__
 #define __SIM_OBJECT_HH__
 
-#include <map>
-#include <list>
-#include <vector>
 #include <iostream>
+#include <list>
+#include <map>
+#include <string>
+#include <vector>
 
 #include "params/SimObject.hh"
 #include "sim/serialize.hh"
diff --git a/src/sim/sim_object_params.hh b/src/sim/sim_object_params.hh
index 4179a37bfb..5a629a949c 100644
--- a/src/sim/sim_object_params.hh
+++ b/src/sim/sim_object_params.hh
@@ -36,6 +36,8 @@
 struct PyObject;
 #endif
 
+#include <string>
+
 struct SimObjectParams
 {
     virtual ~SimObjectParams() {}