diff --git a/legacy/eet/src/lib/eet_cipher.c b/legacy/eet/src/lib/eet_cipher.c
index b529e684db..22dbeec14e 100644
--- a/legacy/eet/src/lib/eet_cipher.c
+++ b/legacy/eet/src/lib/eet_cipher.c
@@ -23,6 +23,7 @@ void *    alloca (size_t);
 #include <string.h>
 #include <sys/types.h>
 #include <sys/stat.h>
+#include <sys/mman.h>
 
 #ifdef HAVE_UNISTD_H
 # include <unistd.h>