diff -upr zsh-5.8.org/Src/utils.c zsh-5.8.mod/Src/utils.c
--- zsh-5.8.org/Src/utils.c	2020-01-13 14:39:15.000000000 +0900
+++ zsh-5.8.mod/Src/utils.c	2021-01-31 09:15:59.741571000 +0900
@@ -7572,3 +7572,29 @@ mailstat(char *path, struct stat *st)
        return 0;
 }
 #endif
+
+#ifdef MULTIBYTE_SUPPORT
+int hack_WC_ISPRINT(const char* s, size_t s_len)
+{
+	const size_t max_len = MB_CUR_MAX;
+	const size_t len = (s_len < max_len) ? s_len : max_len;
+
+	wchar_t pwc[max_len];
+	mbstate_t ps;
+	memset(&ps, 0, sizeof(ps));
+
+	const size_t ret_mbrtowc = mbrtowc(pwc, s, len, &ps);
+
+	switch (ret_mbrtowc) {
+	case MB_INCOMPLETE:
+		return 0;
+	case MB_INVALID:
+		return 0;
+	case 0:
+		return 0;
+	default:
+		return ret_mbrtowc;
+	}
+	return 0;
+}
+#endif
diff -upr zsh-5.8.org/Src/ztype.h zsh-5.8.mod/Src/ztype.h
--- zsh-5.8.org/Src/ztype.h	2020-01-12 04:42:14.000000000 +0900
+++ zsh-5.8.mod/Src/ztype.h	2021-01-31 09:12:59.606155000 +0900
@@ -75,7 +75,8 @@
 # ifdef ENABLE_UNICODE9
 #  define WC_ISPRINT(X)	u9_iswprint(X)
 # else
-#  define WC_ISPRINT(X)	iswprint(X)
+extern int hack_WC_ISPRINT(const char* s, size_t s_len);
+#  define WC_ISPRINT(X)	hack_WC_ISPRINT(&(X), sizeof(X))
 # endif
 #else
 #define WC_ZISTYPE(X,Y)	zistype((X),(Y))