diff --git a/strings/ctype-ucs2.c b/strings/ctype-ucs2.c
index 17bc920a381..8cb8f84f281 100644
--- a/strings/ctype-ucs2.c
+++ b/strings/ctype-ucs2.c
@@ -25,6 +25,10 @@
 
 #ifdef HAVE_CHARSET_ucs2
 
+#ifndef EILSEQ
+#define EILSEQ ENOENT
+#endif
+
 extern MY_UNICASE_INFO *uni_plane[256];
 
 static uchar ctype_ucs2[] = {