https://github.com/termux/termux-packages/issues/15929

--- a/awk.h
+++ b/awk.h
@@ -80,6 +80,11 @@
 
 #ifdef STDC_HEADERS
 #include <stdlib.h>
+#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
 #endif	/* not STDC_HEADERS */
 
 
--- a/support/localeinfo.c
+++ b/support/localeinfo.c
@@ -28,6 +28,11 @@
 #include <limits.h>
 #include <locale.h>
 #include <stdlib.h>
+#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
 #include <string.h>
 #include <wctype.h>
 
--- a/support/regex_internal.h
+++ b/support/regex_internal.h
@@ -23,6 +23,11 @@
 #include <ctype.h>
 #include <stdio.h>
 #include <stdlib.h>
+#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
 #include <string.h>
 
 #include <langinfo.h>
--- a/main.c
+++ b/main.c
@@ -30,6 +30,15 @@
 #include "awk.h"
 #include "getopt.h"
 
+#ifdef __ANDROID__
+static __inline__ char *setlocale_(int category, const char *locale_name) {
+	return setlocale(category, locale_name);
+}
+#define setlocale(category, locale_name) /* */
+#else
+#define setlocale_ setlocale
+#endif
+
 #ifdef HAVE_MCHECK_H
 #include <mcheck.h>
 #endif
@@ -230,6 +239,19 @@
 #if defined(LOCALEDEBUG)
 	const char *initial_locale;
 #endif
+#ifdef __ANDROID__
+	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
 
 	myname = gawk_name(argv[0]);
 
@@ -384,7 +406,7 @@
 		else {
 			gawk_mb_cur_max = 1;	/* hands off my data! */
 #if defined(LC_ALL)
-			setlocale(LC_ALL, "C");
+			setlocale_(LC_ALL, "C");
 #endif
 		}
 	}