diff --git a/dump.c b/dump.c
index 780a2df3f879..97952f46ac7b 100644
--- a/dump.c
+++ b/dump.c
@@ -877,33 +877,36 @@ void
 Perl_dump_sub_perl(pTHX_ const GV *gv, bool justperl)
 {
     CV *cv;
+    PerlIO * debug_log;
+    bool is_gv;
 
     PERL_ARGS_ASSERT_DUMP_SUB_PERL;
 
-    cv = isGV_with_GP(gv) ? GvCV(gv) : CV_FROM_REF((SV*)gv);
+    cv = (is_gv = cBOOL(isGV_with_GP(gv))) ? GvCV(gv) : CV_FROM_REF((SV*)gv);
     if (justperl && (CvISXSUB(cv) || !CvROOT(cv)))
         return;
 
-    if (isGV_with_GP(gv)) {
+    debug_log = Perl_debug_log;
+    if (is_gv) {
         SV * const namesv = newSVpvs_flags("", SVs_TEMP);
         SV *escsv = newSVpvs_flags("", SVs_TEMP);
         const char *namepv;
         STRLEN namelen;
         gv_fullname3(namesv, gv, NULL);
         namepv = SvPV_const(namesv, namelen);
-        Perl_dump_indent(aTHX_ 0, Perl_debug_log, "\nSUB %s = ",
+        Perl_dump_indent(aTHX_ 0, debug_log, "\nSUB %s = ",
                      generic_pv_escape(escsv, namepv, namelen, SvUTF8(namesv)));
     } else {
-        Perl_dump_indent(aTHX_ 0, Perl_debug_log, "\nSUB = ");
+        Perl_dump_indent(aTHX_ 0, debug_log, "\nSUB = ");
     }
     if (CvISXSUB(cv))
-        Perl_dump_indent(aTHX_ 0, Perl_debug_log, "(xsub 0x%" UVxf " %d)\n",
+        Perl_dump_indent(aTHX_ 0, debug_log, "(xsub 0x%" UVxf " %d)\n",
             PTR2UV(CvXSUB(cv)),
             (int)CvXSUBANY(cv).any_i32);
     else if (CvROOT(cv))
         op_dump(CvROOT(cv));
     else
-        Perl_dump_indent(aTHX_ 0, Perl_debug_log, "<undef>\n");
+        Perl_dump_indent(aTHX_ 0, debug_log, "<undef>\n");
 }
 
 /*
@@ -1646,26 +1649,27 @@ Perl_gv_dump(pTHX_ GV *gv)
 {
     STRLEN len;
     const char* name;
+    PerlIO * debug_log = Perl_debug_log;
     SV *sv, *tmp = newSVpvs_flags("", SVs_TEMP);
 
     if (!gv) {
-        PerlIO_printf(Perl_debug_log, "{}\n");
+        PerlIO_printf(debug_log, "{}\n");
         return;
     }
     sv = sv_newmortal();
-    PerlIO_printf(Perl_debug_log, "{\n");
+    PerlIO_printf(debug_log, "{\n");
     gv_fullname3(sv, gv, NULL);
     name = SvPV_const(sv, len);
-    Perl_dump_indent(aTHX_ 1, Perl_debug_log, "GV_NAME = %s",
+    Perl_dump_indent(aTHX_ 1, debug_log, "GV_NAME = %s",
                      generic_pv_escape( tmp, name, len, SvUTF8(sv) ));
     if (gv != GvEGV(gv)) {
         gv_efullname3(sv, GvEGV(gv), NULL);
         name = SvPV_const(sv, len);
-        Perl_dump_indent(aTHX_ 1, Perl_debug_log, "-> %s",
+        Perl_dump_indent(aTHX_ 1, debug_log, "-> %s",
                      generic_pv_escape( tmp, name, len, SvUTF8(sv) ));
     }
-    (void)PerlIO_putc(Perl_debug_log, '\n');
-    Perl_dump_indent(aTHX_ 0, Perl_debug_log, "}\n");
+    (void)PerlIO_putc(debug_log, '\n');
+    Perl_dump_indent(aTHX_ 0, debug_log, "}\n");
 }
 
 
@@ -3022,24 +3026,25 @@ S_deb_padvar(pTHX_ PADOFFSET off, int n, bool paren)
     CV * const cv = deb_curcv(cxstack_ix);
     PADNAMELIST *comppad = NULL;
     int i;
+    PerlIO * debug_log = Perl_debug_log;
 
     if (cv) {
         PADLIST * const padlist = CvPADLIST(cv);
         comppad = PadlistNAMES(padlist);
     }
     if (paren)
-        PerlIO_printf(Perl_debug_log, "(");
+        PerlIO_printf(debug_log, "(");
     for (i = 0; i < n; i++) {
         if (comppad && (sv = padnamelist_fetch(comppad, off + i)))
-            PerlIO_printf(Perl_debug_log, "%" PNf, PNfARG(sv));
+            PerlIO_printf(debug_log, "%" PNf, PNfARG(sv));
         else
-            PerlIO_printf(Perl_debug_log, "[%" UVuf "]",
+            PerlIO_printf(debug_log, "[%" UVuf "]",
                     (UV)(off+i));
         if (i < n - 1)
-            PerlIO_printf(Perl_debug_log, ",");
+            PerlIO_printf(debug_log, ",");
     }
     if (paren)
-        PerlIO_printf(Perl_debug_log, ")");
+        PerlIO_printf(debug_log, ")");
 }
 
 
@@ -3297,12 +3302,15 @@ Implements B<-Dt> perl command line option on OP C<o>.
 I32
 Perl_debop(pTHX_ const OP *o)
 {
+    PerlIO * debug_log;
+
     PERL_ARGS_ASSERT_DEBOP;
 
     if (CopSTASH_eq(PL_curcop, PL_debstash) && !DEBUG_J_TEST_)
         return 0;
 
     Perl_deb(aTHX_ "%s", OP_NAME(o));
+    debug_log = Perl_debug_log;
     switch (o->op_type) {
     case OP_CONST:
     case OP_HINTSEVAL:
@@ -3313,11 +3321,11 @@ Perl_debop(pTHX_ const OP *o)
 #ifdef USE_ITHREADS
         if ((((SVOP*)o)->op_sv) || !IN_PERL_COMPILETIME)
 #endif
-            PerlIO_printf(Perl_debug_log, "(%s)", SvPEEK(cSVOPo_sv));
+            PerlIO_printf(debug_log, "(%s)", SvPEEK(cSVOPo_sv));
         break;
     case OP_GVSV:
     case OP_GV:
-        PerlIO_printf(Perl_debug_log, "(%" SVf ")",
+        PerlIO_printf(debug_log, "(%" SVf ")",
                 SVfARG(S_gv_display(aTHX_ cGVOPo_gv)));
         break;
 
@@ -3334,19 +3342,19 @@ Perl_debop(pTHX_ const OP *o)
         break;
 
     case OP_MULTIDEREF:
-        PerlIO_printf(Perl_debug_log, "(%" SVf ")",
+        PerlIO_printf(debug_log, "(%" SVf ")",
             SVfARG(multideref_stringify(o, deb_curcv(cxstack_ix))));
         break;
 
     case OP_MULTICONCAT:
-        PerlIO_printf(Perl_debug_log, "(%" SVf ")",
+        PerlIO_printf(debug_log, "(%" SVf ")",
             SVfARG(multiconcat_stringify(o)));
         break;
 
     default:
         break;
     }
-    PerlIO_printf(Perl_debug_log, "\n");
+    PerlIO_printf(debug_log, "\n");
     return 0;
 }
 
@@ -3548,9 +3556,12 @@ S_debprof(pTHX_ const OP *o)
 
     if (!DEBUG_J_TEST_ && CopSTASH_eq(PL_curcop, PL_debstash))
         return;
-    if (!PL_profiledata)
-        Newxz(PL_profiledata, MAXO, U32);
-    ++PL_profiledata[o->op_type];
+    U32 * profiledata = PL_profiledata;
+    if (!profiledata) {
+        Newxz(profiledata, MAXO, U32);
+        PL_profiledata = profiledata;
+    }
+    ++profiledata[o->op_type];
 }
 
 /*
@@ -3568,11 +3579,14 @@ Perl_debprofdump(pTHX)
     unsigned i;
     if (!PL_profiledata)
         return;
+    PerlIO * debug_log = Perl_debug_log;
+    U32 * profiledata = PL_profiledata;
+    const char * const * const x_PL_op_names = PL_op_name;
     for (i = 0; i < MAXO; i++) {
-        if (PL_profiledata[i])
-            PerlIO_printf(Perl_debug_log,
-                          "%5lu %s\n", (unsigned long)PL_profiledata[i],
-                                       PL_op_name[i]);
+        if (profiledata[i])
+            PerlIO_printf(debug_log,
+                          "%5lu %s\n", (unsigned long)profiledata[i],
+                                       x_PL_op_names[i]);
     }
 }
 
diff --git a/embed.fnc b/embed.fnc
index 762f47f06c63..977a695088c1 100644
--- a/embed.fnc
+++ b/embed.fnc
@@ -4616,6 +4616,7 @@ S	|const char *|native_querylocale_i				\
 S	|void	|new_LC_ALL	|NN const char *lc_all			\
 				|bool force
 S	|void	|output_check_environment_warning			\
+				|NN PerlIO * const error_log		\
 				|NULLOK const char * const language	\
 				|NULLOK const char * const lc_all	\
 				|NULLOK const char * const lang
diff --git a/embed.h b/embed.h
index 6cb789ce5e02..1a425ceec1cb 100644
--- a/embed.h
+++ b/embed.h
@@ -1377,7 +1377,7 @@
 #       define mortalized_pv_copy(a)            S_mortalized_pv_copy(aTHX_ a)
 #       define native_querylocale_i(a)          S_native_querylocale_i(aTHX_ a)
 #       define new_LC_ALL(a,b)                  S_new_LC_ALL(aTHX_ a,b)
-#       define output_check_environment_warning(a,b,c) S_output_check_environment_warning(aTHX_ a,b,c)
+#       define output_check_environment_warning(a,b,c,d) S_output_check_environment_warning(aTHX_ a,b,c,d)
 #       define parse_LC_ALL_string(a,b,c,d,e,f) S_parse_LC_ALL_string(aTHX_ a,b,c,d,e,f)
 #       define save_to_buffer(a,b,c)            S_save_to_buffer(aTHX_ a,b,c)
 #       define set_save_buffer_min_size(a,b,c)  S_set_save_buffer_min_size(aTHX_ a,b,c)
diff --git a/locale.c b/locale.c
index 4fbefb191071..9114df7e4925 100644
--- a/locale.c
+++ b/locale.c
@@ -8762,16 +8762,17 @@ S_give_perl_locale_control(pTHX_
 }
 
 STATIC void
-S_output_check_environment_warning(pTHX_ const char * const language,
+S_output_check_environment_warning(pTHX_ PerlIO * const error_log,
+                                         const char * const language,
                                          const char * const lc_all,
                                          const char * const lang)
 {
-    PerlIO_printf(Perl_error_log,
+    PerlIO_printf(error_log,
                   "perl: warning: Please check that your locale settings:\n");
 
 #  ifdef __GLIBC__
 
-    PerlIO_printf(Perl_error_log, "\tLANGUAGE = %c%s%c,\n",
+    PerlIO_printf(error_log, "\tLANGUAGE = %c%s%c,\n",
                                   language ? '"' : '(',
                                   language ? language : "unset",
                                   language ? '"' : ')');
@@ -8779,14 +8780,14 @@ S_output_check_environment_warning(pTHX_ const char * const language,
     PERL_UNUSED_ARG(language);
 #  endif
 
-    PerlIO_printf(Perl_error_log, "\tLC_ALL = %c%s%c,\n",
+    PerlIO_printf(error_log, "\tLC_ALL = %c%s%c,\n",
                                   lc_all ? '"' : '(',
                                   lc_all ? lc_all : "unset",
                                   lc_all ? '"' : ')');
 
     for_all_individual_category_indexes(i) {
         const char * value = PerlEnv_getenv(category_names[i]);
-        PerlIO_printf(Perl_error_log,
+        PerlIO_printf(error_log,
                       "\t%s = %c%s%c,\n",
                       category_names[i],
                       value ? '"' : '(',
@@ -8794,11 +8795,11 @@ S_output_check_environment_warning(pTHX_ const char * const language,
                       value ? '"' : ')');
     }
 
-    PerlIO_printf(Perl_error_log, "\tLANG = %c%s%c\n",
+    PerlIO_printf(error_log, "\tLANG = %c%s%c\n",
                                   lang ? '"' : '(',
                                   lang ? lang : "unset",
                                   lang ? '"' : ')');
-    PerlIO_printf(Perl_error_log,
+    PerlIO_printf(error_log,
                   "    are supported and installed on your system.\n");
 }
 
@@ -9211,9 +9212,10 @@ Perl_init_i18nl10n(pTHX_ int printwarn)
         }
 
         if (trial == 0 && locwarn) {
-            PerlIO_printf(Perl_error_log,
+            PerlIO * error_log = Perl_error_log;
+            PerlIO_printf(error_log,
                                   "perl: warning: Setting locale failed.\n");
-            output_check_environment_warning(language, lc_all, lang);
+            output_check_environment_warning(error_log, language, lc_all, lang);
         }
 
 #  else /* Below is ! LC_ALL */
@@ -9247,16 +9249,17 @@ Perl_init_i18nl10n(pTHX_ int printwarn)
         /* Here, this trial failed */
 
         if (dowarn) {
-            PerlIO_printf(Perl_error_log,
+            PerlIO * error_log = Perl_error_log;
+            PerlIO_printf(error_log,
                 "perl: warning: Setting locale failed for the categories:\n");
 
             for_all_individual_category_indexes(j) {
                 if (! curlocales[j]) {
-                    PerlIO_printf(Perl_error_log, "\t%s\n", category_names[j]);
+                    PerlIO_printf(error_log, "\t%s\n", category_names[j]);
                 }
             }
 
-            output_check_environment_warning(language, lc_all, lang);
+            output_check_environment_warning(error_log, language, lc_all, lang);
         }   /* end of warning on first failure */
 
 #  endif /* LC_ALL */
diff --git a/proto.h b/proto.h
index d648766b4898..3e69cf0445d9 100644
--- a/proto.h
+++ b/proto.h
@@ -7187,8 +7187,9 @@ S_new_LC_ALL(pTHX_ const char *lc_all, bool force);
         assert(lc_all)
 
 STATIC void
-S_output_check_environment_warning(pTHX_ const char * const language, const char * const lc_all, const char * const lang);
-#   define PERL_ARGS_ASSERT_OUTPUT_CHECK_ENVIRONMENT_WARNING
+S_output_check_environment_warning(pTHX_ PerlIO * const error_log, const char * const language, const char * const lc_all, const char * const lang);
+#   define PERL_ARGS_ASSERT_OUTPUT_CHECK_ENVIRONMENT_WARNING \
+        assert(error_log)
 
 STATIC parse_LC_ALL_string_return
 S_parse_LC_ALL_string(pTHX_ const char *string, const char **output, const parse_LC_ALL_STRING_action, bool always_use_full_array, const bool panic_on_error, const line_t caller_line);
diff --git a/util.c b/util.c
index b80050479671..b98792eb7dab 100644
--- a/util.c
+++ b/util.c
@@ -4871,23 +4871,24 @@ Perl_debug_hash_seed(pTHX_ bool via_debug_h)
         bool via_env = cBOOL(s && strNE(s, "0") && strNE(s,""));
 
         if ( via_env != via_debug_h ) {
+            PerlIO * debug_log = Perl_debug_log;
             const unsigned char *seed= PERL_HASH_SEED;
             const unsigned char *seed_end= PERL_HASH_SEED + PERL_HASH_SEED_BYTES;
-            PerlIO_printf(Perl_debug_log, "HASH_FUNCTION = %s HASH_SEED = 0x", PERL_HASH_FUNC);
+            PerlIO_printf(debug_log, "HASH_FUNCTION = %s HASH_SEED = 0x", PERL_HASH_FUNC);
             while (seed < seed_end) {
-                PerlIO_printf(Perl_debug_log, "%02x", *seed++);
+                PerlIO_printf(debug_log, "%02x", *seed++);
             }
 #ifdef PERL_HASH_RANDOMIZE_KEYS
-            PerlIO_printf(Perl_debug_log, " PERTURB_KEYS = %d (%s)",
+            PerlIO_printf(debug_log, " PERTURB_KEYS = %d (%s)",
                     PL_HASH_RAND_BITS_ENABLED,
                     PL_HASH_RAND_BITS_ENABLED == 0 ? "NO" :
                     PL_HASH_RAND_BITS_ENABLED == 1 ? "RANDOM"
                                                    : "DETERMINISTIC");
             if (DEBUG_h_TEST)
-                PerlIO_printf(Perl_debug_log,
+                PerlIO_printf(debug_log,
                         " RAND_BITS=0x%" UVxf, PL_hash_rand_bits);
 #endif
-            PerlIO_printf(Perl_debug_log, "\n");
+            PerlIO_printf(debug_log, "\n");
         }
     }
 #endif /* #if (defined(USE_HASH_SEED) ... */