diff --git a/harbour/source/rtl/set.c b/harbour/source/rtl/set.c
index 8afac30a40..0de31353e1 100644
--- a/harbour/source/rtl/set.c
+++ b/harbour/source/rtl/set.c
@@ -8,6 +8,7 @@
 #include <io.h>
 #include <sys/stat.h>
 #include <set.h>
+#include <errno.h>
 
 HB_set_struct hb_set;