diff --git a/sim/main.cc b/sim/main.cc
index 891931c2b8..4352a90f48 100644
--- a/sim/main.cc
+++ b/sim/main.cc
@@ -31,6 +31,7 @@
 ///
 #include <sys/types.h>
 #include <sys/stat.h>
+#include <errno.h>
 #include <libgen.h>
 #include <stdlib.h>
 #include <signal.h>