diff --git a/embed.fnc b/embed.fnc
index c88b1a49daf0..63ea1dde4c97 100644
--- a/embed.fnc
+++ b/embed.fnc
@@ -3080,14 +3080,14 @@ Adfpv	|void	|sv_catpvf_mg	|NN SV * const sv			\
 				|...
 Adp	|void	|sv_catpv_mg	|NN SV * const dsv			\
 				|NULLOK const char * const sstr
-AMbdp	|void	|sv_catpvn	|NN SV *dsv				\
+AMbdp	|void	|sv_catpvn	|NN SV * const dsv			\
 				|NN const char *sstr			\
 				|STRLEN len
 Adp	|void	|sv_catpvn_flags|NN SV * const dsv			\
 				|NN const char *sstr			\
 				|const STRLEN len			\
 				|const I32 flags
-AMbdp	|void	|sv_catpvn_mg	|NN SV *dsv				\
+AMbdp	|void	|sv_catpvn_mg	|NN SV * const dsv			\
 				|NN const char *sstr			\
 				|STRLEN len
 AMbdp	|void	|sv_catsv	|NN SV *dsv				\
@@ -3095,7 +3095,7 @@ AMbdp	|void	|sv_catsv	|NN SV *dsv				\
 Adp	|void	|sv_catsv_flags |NN SV * const dsv			\
 				|NULLOK SV * const sstr 		\
 				|const I32 flags
-AMbdp	|void	|sv_catsv_mg	|NN SV *dsv				\
+AMbdp	|void	|sv_catsv_mg	|NN SV * const dsv			\
 				|NULLOK SV *sstr
 Adp	|void	|sv_chop	|NN SV * const sv			\
 				|NULLOK const char * const ptr
diff --git a/proto.h b/proto.h
index 756486bb0b1c..e38040301108 100644
--- a/proto.h
+++ b/proto.h
@@ -5888,12 +5888,12 @@ Perl_sv_2uv(pTHX_ SV *sv);
         assert(sv)
 
 PERL_CALLCONV void
-Perl_sv_catpvn(pTHX_ SV *dsv, const char *sstr, STRLEN len);
+Perl_sv_catpvn(pTHX_ SV * const dsv, const char *sstr, STRLEN len);
 # define PERL_ARGS_ASSERT_SV_CATPVN             \
         assert(dsv); assert(sstr)
 
 PERL_CALLCONV void
-Perl_sv_catpvn_mg(pTHX_ SV *dsv, const char *sstr, STRLEN len);
+Perl_sv_catpvn_mg(pTHX_ SV * const dsv, const char *sstr, STRLEN len);
 # define PERL_ARGS_ASSERT_SV_CATPVN_MG          \
         assert(dsv); assert(sstr)
 
@@ -5903,7 +5903,7 @@ Perl_sv_catsv(pTHX_ SV *dsv, SV *sstr);
         assert(dsv)
 
 PERL_CALLCONV void
-Perl_sv_catsv_mg(pTHX_ SV *dsv, SV *sstr);
+Perl_sv_catsv_mg(pTHX_ SV * const dsv, SV *sstr);
 # define PERL_ARGS_ASSERT_SV_CATSV_MG           \
         assert(dsv)