diff --git a/src/xz/message.c b/src/xz/message.c
index a87f864d..056ba5ea 100644
--- a/src/xz/message.c
+++ b/src/xz/message.c
@@ -15,6 +15,11 @@
 
 #include <stdarg.h>
 
+#ifdef _MSC_VER
+#	include <io.h>
+#	define isatty _isatty
+#endif
+
 
 /// Number of the current file
 static unsigned int files_pos = 0;
diff --git a/src/xz/util.c b/src/xz/util.c
index 6ab4c2d7..df6fd709 100644
--- a/src/xz/util.c
+++ b/src/xz/util.c
@@ -13,6 +13,11 @@
 #include "private.h"
 #include <stdarg.h>
 
+#ifdef _MSC_VER
+#	include <io.h>
+#	define isatty _isatty
+#endif
+
 
 /// Buffers for uint64_to_str() and uint64_to_nicestr()
 static char bufs[4][128];