1 files changed, 14 insertions, 0 deletions
diff --git a/win32/win32.c b/win32/win32.c
index b212d3874c..1e30ffec9b 100644
--- a/win32/win32.c
+++ b/win32/win32.c
@@ -3424,6 +3424,20 @@ rb_w32_snprintf(char *buf, size_t size, const char *format, ...)
     return ret;
 }
 
+int
+rb_w32_isatty(int fd)
+{
+    if (!(_osfile(fd) & FOPEN)) {
+	errno = EBADF;
+	return 0;
+    }
+    if (!(_osfile(fd) & FDEV)) {
+	errno = ENOTTY;
+	return 0;
+    }
+    return 1;
+}
+
 //
 // Fix bcc32's stdio bug
 //