diff --git a/sim/common/sim-io.c b/sim/common/sim-io.c
index 8c40f7a0e73..874f6423e83 100644
--- a/sim/common/sim-io.c
+++ b/sim/common/sim-io.c
@@ -33,12 +33,12 @@
 #include <unistd.h>
 #endif
 
+#undef open
+
 #include "sim-main.h"
 #include "sim-io.h"
 #include "sim/callback.h"
 
-#undef open
-
 /* Define the rate at which the simulator should poll the host
    for a quit. */
 #ifndef POLL_QUIT_INTERVAL