1 files changed, 4 insertions, 0 deletions
diff --git a/e_os.h b/e_os.h
index 5068d1bd74..25e9e625f0 100644
--- a/e_os.h
+++ b/e_os.h
@@ -408,6 +408,10 @@ static unsigned int _strlen31(const char *str)
 #      define setvbuf(a, b, c, d) setbuffer((a), (b), (d))
        typedef unsigned long clock_t;
 #    endif
+#    ifdef OPENSSL_SYS_WIN32_CYGWIN
+#      include <io.h>
+#      include <fcntl.h>
+#    endif
 
 #    define OPENSSL_CONF	"openssl.cnf"
 #    define SSLEAY_CONF		OPENSSL_CONF