diff --git a/src/fdlib.c b/src/fdlib.c
index a46a2585aebabb06821b38cd010002d9ec0bdc44..f7b749bf535fb39d1279a3590acb3b262e6b8ef8 100644
--- a/src/fdlib.c
+++ b/src/fdlib.c
@@ -2783,7 +2783,7 @@ PMOD_EXPORT int debug_fd_openpty(int *master, int *slave,
   COORD sz;
 
   if (!Pike_NT_CreatePseudoConsole) {
-    errno = ENOENT;
+    errno = ENOTSUPP;
     return -1;
   }