diff --git a/embed.fnc b/embed.fnc
index 505ea6b8af43..bfb3f59f956a 100644
--- a/embed.fnc
+++ b/embed.fnc
@@ -1625,7 +1625,7 @@ Xp	|void	|set_numeric_standard
 Xp	|bool	|_is_in_locale_category|const bool compiling|const int category
 ApdT	|void	|switch_to_global_locale
 ApdT	|bool	|sync_locale
-ApxT	|void	|thread_locale_init
+Apx	|void	|thread_locale_init
 ApxT	|void	|thread_locale_term
 ApdO	|void	|require_pv	|NN const char* pv
 AbpdD	|void	|pack_cat	|NN SV *cat|NN const char *pat|NN const char *patend \
diff --git a/embed.h b/embed.h
index 30d0a21a1215..bb324c4b42c4 100644
--- a/embed.h
+++ b/embed.h
@@ -720,7 +720,7 @@
 #define sync_locale		Perl_sync_locale
 #define taint_env()		Perl_taint_env(aTHX)
 #define taint_proper(a,b)	Perl_taint_proper(aTHX_ a,b)
-#define thread_locale_init	Perl_thread_locale_init
+#define thread_locale_init()	Perl_thread_locale_init(aTHX)
 #define thread_locale_term	Perl_thread_locale_term
 #define to_uni_lower(a,b,c)	Perl_to_uni_lower(aTHX_ a,b,c)
 #define to_uni_title(a,b,c)	Perl_to_uni_title(aTHX_ a,b,c)
diff --git a/locale.c b/locale.c
index b0f38a547622..2141d38fbd9d 100644
--- a/locale.c
+++ b/locale.c
@@ -6645,7 +6645,7 @@ S_setlocale_debug_string_i(const unsigned cat_index,
 #endif
 
 void
-Perl_thread_locale_init()
+Perl_thread_locale_init(pTHX)
 {
     /* Called from a thread on startup*/
 
@@ -6656,8 +6656,6 @@ Perl_thread_locale_init()
      * exacerbating that */                                             \
  && defined(USE_THREAD_SAFE_LOCALE)
 
-    dTHX;
-
     DEBUG_L(PORCELAIN_SETLOCALE_LOCK;
             PerlIO_printf(Perl_debug_log,
                           "new thread, initial locale is %s\n",
diff --git a/proto.h b/proto.h
index dcee31c94130..9f15ad43825c 100644
--- a/proto.h
+++ b/proto.h
@@ -3914,7 +3914,7 @@ PERL_CALLCONV void	Perl_taint_env(pTHX);
 PERL_CALLCONV void	Perl_taint_proper(pTHX_ const char* f, const char *const s);
 #define PERL_ARGS_ASSERT_TAINT_PROPER	\
 	assert(s)
-PERL_CALLCONV void	Perl_thread_locale_init(void);
+PERL_CALLCONV void	Perl_thread_locale_init(pTHX);
 #define PERL_ARGS_ASSERT_THREAD_LOCALE_INIT
 PERL_CALLCONV void	Perl_thread_locale_term(void);
 #define PERL_ARGS_ASSERT_THREAD_LOCALE_TERM