diff --git a/embed.fnc b/embed.fnc
index efe62e6502b7..847226ffcc9c 100644
--- a/embed.fnc
+++ b/embed.fnc
@@ -3785,7 +3785,7 @@ Adip	|bool	|utf8_to_bytes_overwrite				\
 Adip	|bool	|utf8_to_bytes_temp_pv					\
 				|NN U8 const **s_ptr			\
 				|NN STRLEN *lenp
-EMXp	|U8 *	|utf16_to_utf8	|NN U8 *p				\
+Emp	|U8 *	|utf16_to_utf8	|NN U8 *p				\
 				|NN U8 *d				\
 				|Size_t bytelen 			\
 				|NN Size_t *newlen
@@ -3803,7 +3803,7 @@ EXpx	|U8 *	|utf8_to_utf16_base					\
 				|NN Size_t *newlen			\
 				|const bool high			\
 				|const bool low
-EMXp	|U8 *	|utf16_to_utf8_reversed 				\
+Emp	|U8 *	|utf16_to_utf8_reversed 				\
 				|NN U8 *p				\
 				|NN U8 *d				\
 				|Size_t bytelen 			\
diff --git a/embed.h b/embed.h
index fa647eadca0a..d3823463d64a 100644
--- a/embed.h
+++ b/embed.h
@@ -2377,6 +2377,10 @@
 #   define Perl_whichsig(mTHX,a)                whichsig(a)
 #   define thread_locale_init()                 Perl_thread_locale_init(aTHX)
 #   define thread_locale_term()                 Perl_thread_locale_term(aTHX)
+#   if defined(PERL_CORE) || defined(PERL_EXT)
+#     define Perl_utf16_to_utf8(mTHX,a,b,c,d)   utf16_to_utf8(a,b,c,d)
+#     define Perl_utf16_to_utf8_reversed(mTHX,a,b,c,d) utf16_to_utf8_reversed(a,b,c,d)
+#   endif
 #   if defined(PERL_DONT_CREATE_GVSV)
 #     define Perl_gv_SVadd(mTHX,a)              gv_SVadd(a)
 #   endif
@@ -2476,6 +2480,10 @@
 #   define Perl_uvchr_to_utf8_flags_msgs        uvchr_to_utf8_flags_msgs
 #   define Perl_uvoffuni_to_utf8_flags          uvoffuni_to_utf8_flags
 #   define Perl_whichsig                        whichsig
+#   if defined(PERL_CORE) || defined(PERL_EXT)
+#     define Perl_utf16_to_utf8                 utf16_to_utf8
+#     define Perl_utf16_to_utf8_reversed        utf16_to_utf8_reversed
+#   endif
 #   if defined(PERL_DONT_CREATE_GVSV)
 #     define Perl_gv_SVadd                      gv_SVadd
 #   endif
diff --git a/proto.h b/proto.h
index b74a9c7ef985..6888e469508f 100644
--- a/proto.h
+++ b/proto.h
@@ -5328,15 +5328,9 @@ Perl_upg_version(pTHX_ SV *ver, bool qv);
 #define PERL_ARGS_ASSERT_UPG_VERSION            \
         assert(ver)
 
-#define PERL_ARGS_ASSERT_UTF16_TO_UTF8          \
-        assert(p); assert(d); assert(newlen)
-
 #define PERL_ARGS_ASSERT_UTF16_TO_UTF8_BASE     \
         assert(p); assert(d); assert(newlen)
 
-#define PERL_ARGS_ASSERT_UTF16_TO_UTF8_REVERSED \
-        assert(p); assert(d); assert(newlen)
-
 /* PERL_CALLCONV U8 *
 Perl_utf8_hop_back(const U8 *s, SSize_t off, const U8 * const start)
         __attribute__warn_unused_result__; */
@@ -6119,12 +6113,12 @@ Perl_skipspace_flags(pTHX_ char *s, U32 flags)
         __attribute__warn_unused_result__;
 PERL_CALLCONV MAGIC *
 Perl_sv_magicext_mglob(pTHX_ SV *sv);
-PERL_CALLCONV U8 *
-Perl_utf16_to_utf8(pTHX_ U8 *p, U8 *d, Size_t bytelen, Size_t *newlen);
+/* PERL_CALLCONV U8 *
+Perl_utf16_to_utf8(pTHX_ U8 *p, U8 *d, Size_t bytelen, Size_t *newlen); */
 PERL_CALLCONV U8 *
 Perl_utf16_to_utf8_base(pTHX_ U8 *p, U8 *d, Size_t bytelen, Size_t *newlen, const bool high, const bool low);
-PERL_CALLCONV U8 *
-Perl_utf16_to_utf8_reversed(pTHX_ U8 *p, U8 *d, Size_t bytelen, Size_t *newlen);
+/* PERL_CALLCONV U8 *
+Perl_utf16_to_utf8_reversed(pTHX_ U8 *p, U8 *d, Size_t bytelen, Size_t *newlen); */
 PERL_CALLCONV U8 *
 Perl_utf8_to_utf16_base(pTHX_ U8 *s, U8 *d, Size_t bytelen, Size_t *newlen, const bool high, const bool low);
 PERL_CALLCONV bool
diff --git a/utf8.c b/utf8.c
index e2fdc1abc8c6..30f68403a5ed 100644
--- a/utf8.c
+++ b/utf8.c
@@ -3455,22 +3455,6 @@ Perl_utf16_to_utf8_base(pTHX_ U8* p, U8* d, Size_t bytelen, Size_t *newlen,
     return d;
 }
 
-U8*
-Perl_utf16_to_utf8(pTHX_ U8* p, U8* d, Size_t bytelen, Size_t *newlen)
-{
-    PERL_ARGS_ASSERT_UTF16_TO_UTF8;
-
-    return utf16_to_utf8(p, d, bytelen, newlen);
-}
-
-U8*
-Perl_utf16_to_utf8_reversed(pTHX_ U8* p, U8* d, Size_t bytelen, Size_t *newlen)
-{
-    PERL_ARGS_ASSERT_UTF16_TO_UTF8_REVERSED;
-
-    return utf16_to_utf8_reversed(p, d, bytelen, newlen);
-}
-
 /*
  * Convert UTF-8 to native UTF-16. Called via the macros utf8_to_utf16() for
  * big-endian and utf8_to_utf16_reversed() for little-endian,