1 files changed, 10 insertions, 0 deletions
diff --git a/e_os2.h b/e_os2.h
index 2bc0b48798..bd97b921a8 100644
--- a/e_os2.h
+++ b/e_os2.h
@@ -7,6 +7,16 @@
 extern "C" {
 #endif
 
+#include <openssl/opensslconf.h> /* OPENSSL_UNISTD */
+
+#ifdef MSDOS
+# define OPENSSL_UNISTD_IO <io.h>
+# define OPENSSL_DECLARE_EXIT extern void exit(int);
+#else
+# define OPENSSL_UNISTD_IO OPENSSL_UNISTD
+# define OPENSSL_DECLARE_EXIT /* declared in unistd.h */
+#endif
+
 /* Definitions of OPENSSL_GLOBAL and OPENSSL_EXTERN,
    to define and declare certain global
    symbols that, with some compilers under VMS, have to be defined and