1 files changed, 1 insertions, 1 deletions
diff --git a/X11/Xos.h b/X11/Xos.h
index 646716b4f..044d22b4f 100644
--- a/X11/Xos.h
+++ b/X11/Xos.h
@@ -60,7 +60,7 @@ in this Software without prior written authorization from The Open Group.
  */
 
 # include <string.h>
-# if defined(__SCO__) || defined(__UNIXWARE__) || defined(__sun)
+# if defined(__SCO__) || defined(__UNIXWARE__) || defined(__sun) || defined(__CYGWIN__)
 #  include <strings.h>
 # else
 #  ifndef index