This may seem to disregard commit a328a50407c41d634d48c886c4c198465b817d4a.
As stated in the commit message, `setlocale()` can behave in an unexpeced
manner when an empty string (`""`) is specified as its second argument.
Such usage in `sed` program is strictly avoided by the following patch,
and there is no intention to disrespect the aforementioned commit at all.

--- a/lib/stdlib.in.h
+++ b/lib/stdlib.in.h
@@ -1557,3 +1557,9 @@
 #endif /* _@GUARD_PREFIX@_STDLIB_H */
 #endif /* _@GUARD_PREFIX@_STDLIB_H */
 #endif
+
+#if defined __ANDROID__ && defined __TERMUX__
+# undef MB_CUR_MAX
+# define MB_CUR_MAX __ctype_get_mb_cur_max()
+size_t __ctype_get_mb_cur_max(void);
+#endif
--- a/src/grep.c
+++ b/src/grep.c
@@ -2489,7 +2489,26 @@
 
   /* Internationalization. */
 #if defined HAVE_SETLOCALE
+# ifndef __ANDROID__
   setlocale (LC_ALL, "");
+# else /* __ANDROID__ */
+  {
+    const char *locale;
+    locale = getenv ("LC_ALL");
+    if (locale == NULL || locale[0] == '\0')
+      {
+        locale = getenv ("LC_CTYPE");
+        if (locale == NULL || locale[0] == '\0')
+          locale = getenv ("LANG");
+          if (locale == NULL)
+            locale = "";
+      }
+    if (strcmp (locale, "C") == 0 || strcmp (locale, "POSIX") == 0)
+      setlocale (LC_CTYPE, "C");
+    else
+      setlocale (LC_CTYPE, "C.UTF-8");
+  }
+# endif /* __ANDROID__ */
 #endif
 #if defined ENABLE_NLS
   bindtextdomain (PACKAGE, LOCALEDIR);