diff --git a/.github/scripts/badwords.pl b/.github/scripts/badwords.pl
index fe30120a6f..e51d99f0d1 100755
--- a/.github/scripts/badwords.pl
+++ b/.github/scripts/badwords.pl
@@ -13,7 +13,15 @@
 #
 # ---(accepted word)
 #
-my $w;
+
+use strict;
+use warnings;
+
+my @whitelist;
+my %alt;
+my %exactcase;
+
+my @w;
 while(<STDIN>) {
     chomp;
     if($_ =~ /^#/) {
diff --git a/.github/scripts/cleancmd.pl b/.github/scripts/cleancmd.pl
index 283a9f4e93..7b79c2e65a 100755
--- a/.github/scripts/cleancmd.pl
+++ b/.github/scripts/cleancmd.pl
@@ -10,6 +10,11 @@
 # might have a problem with that we still deem is fine.
 #
 
+use strict;
+use warnings;
+
+my @asyms;
+
 open(S, "<./docs/libcurl/symbols-in-versions")
     || die "can't find symbols-in-versions";
 while(<S>) {
diff --git a/.github/scripts/cmp-config.pl b/.github/scripts/cmp-config.pl
index cb47870fe3..88df37b795 100755
--- a/.github/scripts/cmp-config.pl
+++ b/.github/scripts/cmp-config.pl
@@ -23,6 +23,9 @@
 #
 ###########################################################################
 
+use strict;
+use warnings;
+
 my $autotools = $ARGV[0];
 my $cmake = $ARGV[1];
 
diff --git a/.github/scripts/randcurl.pl b/.github/scripts/randcurl.pl
index 84804d6960..c07ba9b7de 100755
--- a/.github/scripts/randcurl.pl
+++ b/.github/scripts/randcurl.pl
@@ -18,6 +18,9 @@
 # directory where it runs.
 #
 
+use strict;
+use warnings;
+
 my $curl = "../src/curl";
 my $url = "localhost:7777"; # not listening to this
 
@@ -31,6 +34,14 @@ if(!$seconds) {
 }
 print "Run $curl for $seconds seconds\n";
 
+my @opt;
+my %arg;
+my %uniq;
+my %allrc;
+
+my $totalargs = 0;
+my $totalcmds = 0;
+
 my $counter = 0xabcdef + time();
 sub getnum {
     my ($max) = @_;
@@ -164,6 +175,7 @@ sub runconfig {
         my $o = getnum($nopts);
         my $option = $opt[$o];
         my $ar = "";
+        $uniq{$option} = 0 if(!exists $uniq{$option});
         $uniq{$option}++;
         if($arg{$option}) {
             $ar = " ".randarg();
diff --git a/.github/scripts/trimmarkdownheader.pl b/.github/scripts/trimmarkdownheader.pl
index 9c623730b9..89b2e7d9fd 100755
--- a/.github/scripts/trimmarkdownheader.pl
+++ b/.github/scripts/trimmarkdownheader.pl
@@ -7,7 +7,10 @@
 # Outputs: the same file, minus the header
 #
 
-my $f = $ARGV[0];
+use strict;
+use warnings;
+
+my $f = $ARGV[0] || '';
 
 open(F, "<$f") or die;
 
diff --git a/.github/scripts/verify-examples.pl b/.github/scripts/verify-examples.pl
index 5853f46b56..27c4de6db8 100755
--- a/.github/scripts/verify-examples.pl
+++ b/.github/scripts/verify-examples.pl
@@ -23,12 +23,15 @@
 #
 ###########################################################################
 
+use strict;
+use warnings;
+
 my @files = @ARGV;
 my $cfile = "test.c";
 my $check = "./scripts/checksrc.pl";
-my $error;
+my $error = 0;
 
-if($files[0] eq "-h") {
+if(!@files || $files[0] eq "-h") {
     print "Usage: verify-examples [markdown pages]\n";
     exit;
 }
@@ -82,7 +85,7 @@ sub extract {
     return ($fail ? 0 : $l);
 }
 
-my $count;
+my $count = 0;
 for my $m (@files) {
     #print "Verify $m\n";
     my $out = extract($m);
diff --git a/.github/scripts/verify-synopsis.pl b/.github/scripts/verify-synopsis.pl
index aa26917946..1c6b00b60b 100755
--- a/.github/scripts/verify-synopsis.pl
+++ b/.github/scripts/verify-synopsis.pl
@@ -23,10 +23,13 @@
 #
 ###########################################################################
 
+use strict;
+use warnings;
+
 my @files = @ARGV;
 my $cfile = "test.c";
 
-if($files[0] eq "-h") {
+if(!@files || $files[0] eq "-h") {
     print "Usage: verify-synopsis [man pages]\n";
     exit;
 }
diff --git a/docs/examples/adddocsref.pl b/docs/examples/adddocsref.pl
index e2e2553dc5..aba9abe2a0 100755
--- a/docs/examples/adddocsref.pl
+++ b/docs/examples/adddocsref.pl
@@ -25,9 +25,12 @@
 
 # pass files as argument(s)
 
+use strict;
+use warnings;
+
 my $docroot="https://curl.se/libcurl/c";
 
-for $f (@ARGV) {
+for my $f (@ARGV) {
     open(NEW, ">$f.new");
     open(F, "<$f");
     while(<F>) {
diff --git a/docs/examples/version-check.pl b/docs/examples/version-check.pl
index 932d154bdb..bc065770bc 100755
--- a/docs/examples/version-check.pl
+++ b/docs/examples/version-check.pl
@@ -38,6 +38,9 @@
 #    version-check.pl [source file]
 #
 
+use strict;
+use warnings;
+
 open(S, "<../libcurl/symbols-in-versions") || die;
 
 my %doc;
@@ -64,7 +67,7 @@ sub age {
     my ($ver)=@_;
 
     my @s=split(/\./, $ver);
-    return $s[0]*10000+$s[1]*100+$s[2];
+    return $s[0]*10000+$s[1]*100+($s[2] || 0);
 }
 
 my %used;
diff --git a/docs/libcurl/mksymbolsmanpage.pl b/docs/libcurl/mksymbolsmanpage.pl
index a79688953c..c70e994957 100755
--- a/docs/libcurl/mksymbolsmanpage.pl
+++ b/docs/libcurl/mksymbolsmanpage.pl
@@ -22,6 +22,8 @@
 # * SPDX-License-Identifier: curl
 # *
 # ***************************************************************************
+use strict;
+use warnings;
 
 use POSIX qw(strftime);
 my @ts;
diff --git a/docs/libcurl/symbols.pl b/docs/libcurl/symbols.pl
index 1105ae66b6..1751a4887d 100755
--- a/docs/libcurl/symbols.pl
+++ b/docs/libcurl/symbols.pl
@@ -44,12 +44,15 @@
 # #endif
 #
 #
+use strict;
+use warnings;
+
 open F, "<symbols-in-versions";
 
 sub str2num {
     my ($str)=@_;
-    if($str =~ /([0-9]*)\.([0-9]*)\.*([0-9]*)/) {
-        return sprintf("0x%06x", $1<<16 | $2 << 8 | $3);
+    if($str && $str =~ /([0-9]*)\.([0-9]*)\.*([0-9]*)/) {
+        return sprintf("0x%06x", $1 <<16 | $2 << 8 | ($3 || '0'));
     }
 }
 
diff --git a/lib/optiontable.pl b/lib/optiontable.pl
index cc38a922cc..43fbd39d3b 100755
--- a/lib/optiontable.pl
+++ b/lib/optiontable.pl
@@ -1,5 +1,8 @@
 #!/usr/bin/env perl
 
+use strict;
+use warnings;
+
 print <<HEAD
 /***************************************************************************
  *                                  _   _ ____  _
@@ -37,31 +40,36 @@ HEAD
 
 my $lastnum=0;
 
+my %opt;
+my %type;
+my @names;
+my %alias;
+
 sub add {
-    my($opt, $type, $num)=@_;
+    my($optstr, $typestr, $num)=@_;
     my $name;
     # remove all spaces from the type
-    $type =~ s/ //g;
-    my $ext = $type;
+    $typestr =~ s/ //g;
+    my $ext = $typestr;
 
-    if($opt =~ /OBSOLETE/) {
+    if($optstr =~ /OBSOLETE/) {
         # skip obsolete options
         next;
     }
 
-    if($opt =~ /^CURLOPT_(.*)/) {
+    if($optstr =~ /^CURLOPT_(.*)/) {
         $name=$1;
     }
     $ext =~ s/CURLOPTTYPE_//;
     $ext =~ s/CBPOINT/CBPTR/;
     $ext =~ s/POINT\z//;
-    $type = "CURLOT_$ext";
+    $typestr = "CURLOT_$ext";
 
-    $opt{$name} = $opt;
-    $type{$name} = $type;
+    $opt{$name} = $optstr;
+    $type{$name} = $typestr;
     push @names, $name;
     if($num < $lastnum) {
-        print STDERR "ERROR: $opt has bad number: $num < $lastnum\n";
+        print STDERR "ERROR: $optstr has bad number: $num < $lastnum\n";
         exit 2;
     }
     else {
@@ -123,8 +131,8 @@ for my $name (sort @names) {
         $name = $alias{$name};
         $flag = "CURLOT_FLAG_ALIAS";
     }
-    $o = sprintf("  {\"%s\", %s, %s, %s},\n",
-                 $oname, $opt{$name}, $type{$name}, $flag);
+    my $o = sprintf("  {\"%s\", %s, %s, %s},\n",
+                    $oname, $opt{$name}, $type{$name}, $flag);
     if(length($o) < 80) {
         print $o;
     }
diff --git a/scripts/cd2cd b/scripts/cd2cd
index 3eaa0219e7..f4748f5d9b 100755
--- a/scripts/cd2cd
+++ b/scripts/cd2cd
@@ -36,13 +36,16 @@ Example: cd2cd [--in-place] <file.md> > <file.md>
 =end comment
 =cut
 
+use strict;
+use warnings;
+
 my $cd2cd = "0.1"; # to keep check
 my $dir;
 my $extension;
 my $inplace = 0;
 
 while(1) {
-    if($ARGV[0] eq "--in-place") {
+    if(@ARGV && $ARGV[0] eq "--in-place") {
         shift @ARGV;
         $inplace = 1;
     }
@@ -84,6 +87,9 @@ sub single {
     my $start = 0;
     my $d;
     my $line = 0;
+    my $salist = 0;
+    my $copyright;
+    my $spdx;
     open(F, "<:crlf", "$f") ||
         return 1;
     while(<F>) {
@@ -221,6 +227,6 @@ if($inplace) {
         single($a);
     }
 }
-else {
+elsif(@ARGV) {
     exit single($ARGV[0]);
 }
diff --git a/scripts/cdall b/scripts/cdall
index 507ccc6be2..aab41b6505 100755
--- a/scripts/cdall
+++ b/scripts/cdall
@@ -25,6 +25,9 @@
 
 # provide all dir names to scan on the cmdline
 
+use strict;
+use warnings;
+
 sub convert {
     my ($dir)=@_;
     opendir(my $dh, $dir) || die "could not open $dir";
diff --git a/scripts/ciconfig.pl b/scripts/ciconfig.pl
index 93358def21..1d8f235564 100755
--- a/scripts/ciconfig.pl
+++ b/scripts/ciconfig.pl
@@ -23,6 +23,14 @@
 #
 ###########################################################################
 
+use strict;
+use warnings;
+
+my %with;
+my %without;
+my %used;
+my %avail;
+
 # these options are enabled by default in the sense that they will attempt to
 # check for and use this feature without the configure flag
 my %defaulton = (
diff --git a/scripts/cijobs.pl b/scripts/cijobs.pl
index 56916bcd82..2be9d2565c 100755
--- a/scripts/cijobs.pl
+++ b/scripts/cijobs.pl
@@ -23,6 +23,9 @@
 #
 ###########################################################################
 
+use strict;
+use warnings;
+
 my %filelevel= ('file' => 1,
                 'service' => 1);
 
@@ -39,6 +42,8 @@ sub submit {
     }
 }
 
+my %job;
+
 sub githubactions {
     my ($tag)=@_;
     my @files= `git ls-tree -r --name-only $tag .github/workflows 2>/dev/null`;
@@ -341,6 +346,8 @@ sub circle {
     my $cmds;
     my $jobs;
     my $workflow;
+    my $cmdname;
+    my $jobname;
     $job{'file'} = ".circleci/config.yml";
     $job{'service'} = "circleci";
     while(<G>) {
@@ -408,6 +415,10 @@ sub zuul {
     my %job;
     my $line=0;
     my $type;
+    my $jobmode;
+    my $apt = 0;
+    my $env = 0;
+    my $envcont;
     $job{'file'} = "zuul.d/jobs.yaml";
     $job{'service'} = "zuul";
     while(<G>) {
diff --git a/scripts/delta b/scripts/delta
index f950077774..3aab7e5795 100755
--- a/scripts/delta
+++ b/scripts/delta
@@ -30,6 +30,9 @@
 #
 # In the git clone root, invoke 'scripts/delta [release tag]'
 
+use strict;
+use warnings;
+
 $start = $ARGV[0];
 
 if($start eq "-h") {
diff --git a/scripts/extract-unit-protos b/scripts/extract-unit-protos
index 48fa1e8791..80c2831ede 100755
--- a/scripts/extract-unit-protos
+++ b/scripts/extract-unit-protos
@@ -23,6 +23,12 @@
 #
 ###########################################################################
 
+use strict;
+use warnings;
+
+my @proto;
+my %inc;
+
 sub scanfile {
     my ($file) = @_;
     open(F, "<$file") || die "$file failed";
diff --git a/scripts/managen b/scripts/managen
index bf5bca5b1a..e4fccdc065 100755
--- a/scripts/managen
+++ b/scripts/managen
@@ -39,6 +39,9 @@ Unfortunately it seems some perls like msysgit cannot handle a global input-only
 =end comment
 =cut
 
+use strict;
+use warnings;
+
 my %optshort;
 my %optlong;
 my %helplong;
@@ -65,7 +68,7 @@ my $indent = 4;
 sub manpageify {
     my ($k)=@_;
     my $l;
-    my $trail;
+    my $trail = '';
     # the matching pattern might include a trailing dot that cannot be part of
     # the option name
     if($k =~ s/\.$//) {
@@ -127,8 +130,10 @@ sub justline {
 
 sub lastline {
     my ($lvl, @line) = @_;
+    my $l = 0;
     $line[0] =~ s/^( +)//;
-    prefixline($lvl * $indent + length($1));
+    $l = length($1) if($1);
+    prefixline($lvl * $indent + $l);
     my $prev = 0;
     for(@line) {
         printf "%s%s", $prev?" ":"", $_;
@@ -174,9 +179,11 @@ sub printdesc {
     }
     else {
         my $p = -1;
-        my $para;
+        my $pnum;
+        my $para = '';
         for my $l (@desc) {
-            my $lvl;
+            my $lvl = 0;
+            my $lvlnum;
             if($l !~ /^[\n\r]+/) {
                 # get the indent level off the string
                 $l =~ s/^\[([0-9q]*)\]//;
@@ -186,15 +193,19 @@ sub printdesc {
                 # the previous was quoted, this is not
                 print "\n";
             }
-            if($lvl != $p) {
-                outputpara($baselvl + $p, $para);
+            if($lvl ne $p) {
+                $pnum = $p;
+                $pnum =~ s/q$//;
+                outputpara($baselvl + $pnum, $para);
                 $para = "";
             }
             if($lvl =~ /q/) {
                 # quoted, do not right-justify
                 chomp $l;
-                lastline($baselvl + $lvl + 1, $l);
-                my $w = ($baselvl + $lvl + 1) * $indent + length($l);
+                $lvlnum = $lvl;
+                $lvlnum =~ s/q$//;
+                lastline($baselvl + $lvlnum + 1, $l);
+                my $w = ($baselvl + $lvlnum + 1) * $indent + length($l);
                 if($w > $colwidth) {
                     print STDERR "ERROR: $w columns is too long\n";
                     print STDERR "$l\n";
@@ -207,7 +218,9 @@ sub printdesc {
 
             $p = $lvl;
         }
-        outputpara($baselvl + $p, $para);
+        $pnum = $p;
+        $pnum =~ s/q$//;
+        outputpara($baselvl + $pnum, $para);
     }
 }
 
@@ -281,10 +294,11 @@ sub render {
     my $header = 0;
     # if $top is TRUE, it means a top-level page and not a command line option
     my $top = ($line == 1);
-    my $quote;
-    my $level;
+    my $quote = 0;
+    my $level = 0;
     my $finalblank;
-    $start = 0;
+    my $blankline = 0;
+    my $start = 0;
 
     while(<$fh>) {
         my $d = $_;
@@ -575,7 +589,7 @@ sub single {
             $protocols=$1;
         }
         elsif(/^See-also: +(.+)/i) {
-            if($seealso) {
+            if(@seealso) {
                 print STDERR "ERROR: duplicated See-also in $f\n";
                 return 1;
             }
@@ -666,10 +680,6 @@ sub single {
 
     my @desc = render($manpage, $fh, $f, $line);
     close($fh);
-    if($tablemode) {
-        # end of table
-        push @desc, ".RE\n.IP\n";
-    }
     my $opt;
 
     if(defined($short) && $long) {
@@ -802,7 +812,7 @@ sub single {
         my @m=split(/ /, $mutexed);
         my $mstr;
         my $num = scalar(@m);
-        my $count;
+        my $count = 0;
         for my $k (@m) {
             if(!$helplong{$k}) {
                 print STDERR "WARN: $f mutexes a non-existing option: $k\n";
@@ -876,13 +886,13 @@ sub single {
     push @foot, seealso($standalone, $mstr);
 
     print "\n";
-    my $f = join("", @foot);
+    my $ft = join("", @foot);
     if($manpage) {
-        $f =~ s/ +\z//; # remove trailing space
-        print "$f\n";
+        $ft =~ s/ +\z//; # remove trailing space
+        print "$ft\n";
     }
     else {
-        printdesc($manpage, 2, "[1]$f");
+        printdesc($manpage, 2, "[1]$ft");
     }
     return 0;
 }
@@ -950,8 +960,8 @@ sub getshortlong {
 
 sub indexoptions {
     my ($dir, @files) = @_;
-    foreach my $f (@files) {
-        getshortlong($dir, $f);
+    foreach my $file (@files) {
+        getshortlong($dir, $file);
     }
 }
 
@@ -1122,7 +1132,6 @@ sub listglobals {
         }
         close(F);
     }
-    return $ret if($ret);
     for my $e (0 .. $#globalopts) {
         $globals .= sprintf "%s--%s",  $e?($globalopts[$e+1] ? ", " : " and "):"",
             $globalopts[$e],;
@@ -1257,7 +1266,7 @@ sub getargs {
 
 my $dir = ".";
 my $include = "../../include";
-my $cmd = shift @ARGV;
+my $cmd = shift @ARGV || '';
 
  check:
 if($cmd eq "-d") {
diff --git a/scripts/mdlinkcheck b/scripts/mdlinkcheck
index 33fcac9de6..f5b123a24a 100755
--- a/scripts/mdlinkcheck
+++ b/scripts/mdlinkcheck
@@ -23,6 +23,9 @@
 #
 ###########################################################################
 
+use strict;
+use warnings;
+
 my %whitelist = (
     'https://curl.se/' => 1,
     'https://curl.se/changes.html' => 1,
@@ -70,6 +73,9 @@ my %whitelist = (
 
     );
 
+my %url;
+my %flink;
+
 # list all .md files in the repo
 my @files=`git ls-files '**.md'`;
 
@@ -127,6 +133,7 @@ sub checkurl {
 
     print "check $url\n";
     my $curlcmd="curl -ILfsm10 --retry 2 --retry-delay 5 -A \"Mozilla/curl.se link-probe\"";
+    $url =~ s/\+/%2B/g;
     my @content = `$curlcmd \"$url\"`;
     if(!$content[0]) {
         print STDERR "FAIL\n";
@@ -146,7 +153,7 @@ for my $u (sort keys %url) {
     my $r = checkurl($u);
 
     if($r) {
-        for my $f (split(/ /, $url{$l})) {
+        for my $f (split(/ /, $url{$u})) {
             printf "%s ERROR links to missing URL %s\n", $f, $u;
             $error++;
         }
diff --git a/scripts/nroff2cd b/scripts/nroff2cd
index 17361b227b..b0308b6ef0 100755
--- a/scripts/nroff2cd
+++ b/scripts/nroff2cd
@@ -36,6 +36,9 @@ for code.
 =end comment
 =cut
 
+use strict;
+use warnings;
+
 my $nroff2cd = "0.1"; # to keep check
 
 sub single {
@@ -189,4 +192,6 @@ HEAD
     return !$header;
 }
 
-exit single($ARGV[0]);
+if(@ARGV) {
+  exit single($ARGV[0]);
+}
diff --git a/scripts/randdisable b/scripts/randdisable
index f8a7a147ed..1ccaf6f10d 100755
--- a/scripts/randdisable
+++ b/scripts/randdisable
@@ -20,8 +20,13 @@
 # - edit the @tls array to include all TLS backends you can build with
 # - do a checkout in a ram-based filesystem
 #
+use strict;
+use warnings;
+
 use List::Util qw/shuffle/;
 
+my @disable;
+
 sub getoptions {
     my @all = `./configure --help`;
     for my $o (@all) {
diff --git a/scripts/release-notes.pl b/scripts/release-notes.pl
index 741235a3e6..331941bc9b 100755
--- a/scripts/release-notes.pl
+++ b/scripts/release-notes.pl
@@ -54,7 +54,10 @@
 #
 ################################################
 
-my $cleanup = ($ARGV[0] eq "cleanup");
+use strict;
+use warnings;
+
+my $cleanup = (@ARGV && $ARGV[0] eq "cleanup");
 my @gitlog=`git log @^{/RELEASE-NOTES:.synced}..` if(!$cleanup);
 my @releasenotes=`cat RELEASE-NOTES`;
 
@@ -120,6 +123,12 @@ sub extract {
     # false alarm, not a valid line
 }
 
+my @fixes;
+my @closes;
+my @bug;
+my @line;
+my %moreinfo;
+
 my $short;
 my $first;
 for my $l (@gitlog) {
@@ -167,7 +176,7 @@ if($first) {
 # call at the end of a parsed commit
 sub onecommit {
     my ($short)=@_;
-    my $ref;
+    my $ref = '';
 
     if($dupe{$short}) {
         # this git commit message was found in the file
diff --git a/scripts/singleuse.pl b/scripts/singleuse.pl
index 0251594b12..6156496019 100755
--- a/scripts/singleuse.pl
+++ b/scripts/singleuse.pl
@@ -33,13 +33,16 @@
 # --unit : built to support unit tests
 #
 
+use strict;
+use warnings;
+
 my $unittests;
-if($ARGV[0] eq "--unit") {
+if(@ARGV && $ARGV[0] eq "--unit") {
     $unittests = "tests/unit ";
     shift @ARGV;
 }
 
-my $file = $ARGV[0];
+my $file = $ARGV[0] || '';
 
 my %wl = (
     'Curl_xfer_write_resp' => 'internal api',
@@ -178,7 +181,6 @@ open(N, "nm $file|") ||
 
 my %exist;
 my %uses;
-my $file;
 while(<N>) {
     my $l = $_;
     chomp $l;
@@ -204,7 +206,7 @@ while(<N>) {
 }
 close(N);
 
-my $err;
+my $err = 0;
 for(sort keys %exist) {
     #printf "%s is defined in %s, used by: %s\n", $_, $exist{$_}, $uses{$_};
     if(!$uses{$_}) {
diff --git a/src/mk-file-embed.pl b/src/mk-file-embed.pl
index 17530cfa14..fcd8e04136 100755
--- a/src/mk-file-embed.pl
+++ b/src/mk-file-embed.pl
@@ -23,8 +23,11 @@
 #
 ###########################################################################
 
+use strict;
+use warnings;
+
 my $varname = "var";
-if($ARGV[0] eq "--var") {
+if(@ARGV && $ARGV[0] eq "--var") {
     shift;
     $varname = shift @ARGV;
 }
diff --git a/src/mkhelp.pl b/src/mkhelp.pl
index 782c466524..d1a040c0cc 100755
--- a/src/mkhelp.pl
+++ b/src/mkhelp.pl
@@ -23,11 +23,17 @@
 #
 ###########################################################################
 
-if($ARGV[0] eq "-c") {
-    $c=1;
+use strict;
+use warnings;
+
+my $c = 0;
+if(@ARGV && $ARGV[0] eq "-c") {
+    $c = 1;
     shift @ARGV;
 }
 
+my @out;
+
 push @out, "          _   _ ____  _\n";
 push @out, "      ___| | | |  _ \\| |\n";
 push @out, "     / __| | | | |_) | |\n";
@@ -67,8 +73,8 @@ if($c)
     my $gzippedContent;
     IO::Compress::Gzip::gzip(
         \$content, \$gzippedContent, Level => 9, TextFlag => 1, Time=>0) or die "gzip failed:";
-    $gzip = length($content);
-    $gzipped = length($gzippedContent);
+    my $gzip = length($content);
+    my $gzipped = length($gzippedContent);
 
     print <<HEAD
 #include <zlib.h>
diff --git a/tests/allversions.pm b/tests/allversions.pm
index f38612403c..7673a5fcca 100644
--- a/tests/allversions.pm
+++ b/tests/allversions.pm
@@ -22,9 +22,14 @@
 #
 ###########################################################################
 
-# populate the has %pastversion hash table with the version number as key and
+# populate the %pastversion hash table with the version number as key and
 # release date as value
 
+use strict;
+use warnings;
+
+our %pastversion;
+
 sub allversions {
     my ($file) = @_;
     open(A, "<$file") ||
diff --git a/tests/http2-server.pl b/tests/http2-server.pl
index 8762000333..1a36a8b1f6 100755
--- a/tests/http2-server.pl
+++ b/tests/http2-server.pl
@@ -23,6 +23,9 @@
 #
 #***************************************************************************
 
+use strict;
+use warnings;
+
 # This script invokes nghttpx properly to have it serve HTTP/2 for us.
 # nghttpx runs as a proxy in front of our "actual" HTTP/1 server.
 use Cwd;
diff --git a/tests/http3-server.pl b/tests/http3-server.pl
index b78d712b32..6b3de3d748 100755
--- a/tests/http3-server.pl
+++ b/tests/http3-server.pl
@@ -23,6 +23,9 @@
 #
 #***************************************************************************
 
+use strict;
+use warnings;
+
 # This script invokes nghttpx properly to have it serve HTTP/3 for us.
 # nghttpx runs as a proxy in front of our "actual" HTTP/1 server.
 
diff --git a/tests/libtest/mk-lib1521.pl b/tests/libtest/mk-lib1521.pl
index 8f207a2d14..0dc4fe15e0 100755
--- a/tests/libtest/mk-lib1521.pl
+++ b/tests/libtest/mk-lib1521.pl
@@ -22,6 +22,8 @@
 # SPDX-License-Identifier: curl
 #
 ###########################################################################
+use strict;
+use warnings;
 
 # Usage:
 #   perl mk-lib1521.pl < ../../include/curl/curl.h lib1521.c
@@ -363,6 +365,8 @@ static CURLcode test_lib1521(char *URL)
 HEADER
     ;
 
+my $infomode = 0;
+
 while(<STDIN>) {
     s/^\s*(.*?)\s*$/$1/;      # Trim.
     # Remove multi-line comment trail.
diff --git a/tests/libtest/test1013.pl b/tests/libtest/test1013.pl
index 878077d80c..b97341d0cb 100755
--- a/tests/libtest/test1013.pl
+++ b/tests/libtest/test1013.pl
@@ -22,6 +22,9 @@
 # SPDX-License-Identifier: curl
 #
 ###########################################################################
+use strict;
+use warnings;
+
 # Determine if curl-config --protocols/--features matches the
 # curl --version protocols/features
 if($#ARGV != 2) {
@@ -41,7 +44,7 @@ close CURL;
 
 $curl_protocols =~ s/\r//;
 $curl_protocols =~ /\w+: (.*)$/;
-@curl = split / /,$1;
+my @curl = split / /,$1;
 
 # Read the output of curl-config
 my @curl_config;
diff --git a/tests/libtest/test1022.pl b/tests/libtest/test1022.pl
index 4427d633b5..e1c3cd598e 100755
--- a/tests/libtest/test1022.pl
+++ b/tests/libtest/test1022.pl
@@ -22,6 +22,9 @@
 # SPDX-License-Identifier: curl
 #
 ###########################################################################
+use strict;
+use warnings;
+
 # Determine if curl-config --version matches the curl --version
 if($#ARGV != 2) {
     print "Usage: $0 curl-config-script curl-version-output-file version|vernum\n";
diff --git a/tests/libtest/test307.pl b/tests/libtest/test307.pl
index ea54b59824..5a0a97a3a6 100755
--- a/tests/libtest/test307.pl
+++ b/tests/libtest/test307.pl
@@ -22,12 +22,15 @@
 # SPDX-License-Identifier: curl
 #
 ###########################################################################
+use strict;
+use warnings;
+
 # Determine if the given curl executable supports the 'openssl' SSL engine
 if($#ARGV != 0) {
     print "Usage: $0 curl-executable\n";
     exit 3;
 }
-if(!open(CURL, "@ARGV[0] -s --engine list|")) {
+if(!open(CURL, "$ARGV[0] -s --engine list|")) {
     print "Can't get SSL engine list\n";
     exit 2;
 }
diff --git a/tests/libtest/test610.pl b/tests/libtest/test610.pl
index b37c25286a..10f665620a 100755
--- a/tests/libtest/test610.pl
+++ b/tests/libtest/test610.pl
@@ -22,6 +22,9 @@
 # SPDX-License-Identifier: curl
 #
 ###########################################################################
+use strict;
+use warnings;
+
 # Perform simple file and directory manipulation in a portable way
 if($#ARGV <= 0) {
     print "Usage: $0 mkdir|rmdir|rm|move|gone path1 [path2] [more commands...]\n";
diff --git a/tests/libtest/test613.pl b/tests/libtest/test613.pl
index 9abc0c41cd..429168abfc 100755
--- a/tests/libtest/test613.pl
+++ b/tests/libtest/test613.pl
@@ -22,6 +22,9 @@
 # SPDX-License-Identifier: curl
 #
 ###########################################################################
+use strict;
+use warnings;
+
 # Prepare a directory with known files and clean up afterwards
 use Time::Local;
 
diff --git a/tests/memanalyze.pl b/tests/memanalyze.pl
index 339da664e0..e794972a33 100755
--- a/tests/memanalyze.pl
+++ b/tests/memanalyze.pl
@@ -29,17 +29,22 @@
 # MEM mprintf.c:1103 realloc(e5718, 64) = e6118
 # MEM sendf.c:232 free(f6520)
 
+use strict;
+use warnings;
+
 my $mallocs=0;
 my $callocs=0;
 my $reallocs=0;
 my $strdups=0;
 my $wcsdups=0;
-my $showlimit;
+my $showlimit=0;
 my $sends=0;
 my $recvs=0;
 my $sockets=0;
+my $verbose=0;
+my $trace=0;
 
-while(1) {
+while(@ARGV) {
     if($ARGV[0] eq "-v") {
         $verbose=1;
         shift @ARGV;
@@ -70,7 +75,7 @@ sub newtotal {
     }
 }
 
-my $file = $ARGV[0];
+my $file = $ARGV[0] || '';
 
 if(! -f $file) {
     print "Usage: memanalyze.pl [options] <dump file>\n",
@@ -94,11 +99,36 @@ if($showlimit) {
     exit;
 }
 
+my %sizeataddr;
+my %getmem;
 
-my $lnum=0;
+my $totalmem = 0;
+my $frees = 0;
+
+my $dup;
+my $size;
+my $addr;
+
+my %filedes;
+my %getfile;
+
+my %fopen;
+my %fopenfile;
+my $openfile = 0;
+my $fopens = 0;
+
+my %addrinfo;
+my %addrinfofile;
+my $addrinfos = 0;
+
+my $source;
+my $linenum;
+my $function;
+
+my $lnum = 0;
 while(<$fileh>) {
     chomp $_;
-    $line = $_;
+    my $line = $_;
     $lnum++;
     if($line =~ /^LIMIT ([^ ]*):(\d*) (.*)/) {
         # new memory limit test prefix
@@ -145,13 +175,13 @@ while(<$fileh>) {
             $size = $1;
             $addr = $2;
 
-            if($sizeataddr{$addr}>0) {
+            if($sizeataddr{$addr} && $sizeataddr{$addr}>0) {
                 # this means weeeeeirdo
                 print "Mixed debug compile ($source:$linenum at line $lnum), rebuild curl now\n";
                 print "We think $sizeataddr{$addr} bytes are already allocated at that memory address: $addr!\n";
             }
 
-            $sizeataddr{$addr}=$size;
+            $sizeataddr{$addr} = $size;
             $totalmem += $size;
             $memsum += $size;
 
@@ -169,8 +199,8 @@ while(<$fileh>) {
             $size = $1*$2;
             $addr = $3;
 
-            $arg1 = $1;
-            $arg2 = $2;
+            my $arg1 = $1;
+            my $arg2 = $2;
 
             if($sizeataddr{$addr}>0) {
                 # this means weeeeeirdo
diff --git a/tests/runtests.pl b/tests/runtests.pl
index 3908c1a25a..dfa35aaea5 100755
--- a/tests/runtests.pl
+++ b/tests/runtests.pl
@@ -1722,7 +1722,7 @@ sub singletest_check {
                 $ok .= "m";
             }
             my @more=`$memanalyze -v "$logdir/$MEMDUMP"`;
-            my $allocs;
+            my $allocs = 0;
             my $max = 0;
             for(@more) {
                 if(/^Allocations: (\d+)/) {
diff --git a/tests/test1140.pl b/tests/test1140.pl
index ac06c4af30..8900ef439f 100755
--- a/tests/test1140.pl
+++ b/tests/test1140.pl
@@ -26,7 +26,10 @@
 # scan manpages to find basic syntactic problems such as unbalanced \f
 # codes or references to non-existing curl manpages.
 
-my $docsroot = $ARGV[0];
+use strict;
+use warnings;
+
+my $docsroot = $ARGV[0] || '.';
 
 if(!$docsroot || ($docsroot eq "-g")) {
     print "Usage: test1140.pl <docs root dir> [manpages]\n";
@@ -40,6 +43,8 @@ my @f = @ARGV;
 
 my %manp;
 
+my $errors = 0;
+
 sub manpresent {
     my ($man) = @_;
     if($manp{$man}) {
@@ -111,4 +116,4 @@ foreach my $f (@f) {
 
 print "OK\n" if(!$errors);
 
-exit $errors?1:0;
+exit ($errors ? 1 : 0);
diff --git a/tests/test1175.pl b/tests/test1175.pl
index c981046b7e..2e67142613 100755
--- a/tests/test1175.pl
+++ b/tests/test1175.pl
@@ -27,7 +27,7 @@ use strict;
 use warnings;
 
 # we may get the dir root pointed out
-my $root=$ARGV[0] || ".";
+my $root = $ARGV[0] || ".";
 
 my %error; # from the include file
 my %docs; # from libcurl-errors.3
diff --git a/tests/test1275.pl b/tests/test1275.pl
index e5f54c627e..d9429ea3dc 100755
--- a/tests/test1275.pl
+++ b/tests/test1275.pl
@@ -23,11 +23,14 @@
 #
 ###########################################################################
 
+use strict;
+use warnings;
+
 my $root=$ARGV[0] || "..";
 
 my @m = `git ls-files -- $root`;
 
-my $errors;
+my $errors = 0;
 
 my %accepted=('curl' => 1,
               'libcurl' => 1,
@@ -45,7 +48,7 @@ sub checkfile {
     }
     open(my $fh, "<", "$f");
     my $l;
-    my $prevl;
+    my $prevl = '';
     my $ignore = 0;
     my $metadata = 0;
     while(<$fh>) {
diff --git a/tests/test1276.pl b/tests/test1276.pl
index 74d4651734..3eb04c035f 100755
--- a/tests/test1276.pl
+++ b/tests/test1276.pl
@@ -23,13 +23,16 @@
 #
 ###########################################################################
 
+use strict;
+use warnings;
+
 sub showline {
     my ($l) = @_;
     $l =~ s/([^\x20-\x7f])/sprintf "%%%02x", ord $1/eg;
     return $l;
 }
 
-my $root = $ARGV[0];
+my $root = $ARGV[0] || '..';
 
 open(my $fh, "-|", "perl $root/lib/optiontable.pl < $root/include/curl/curl.h");
 binmode $fh;
diff --git a/tests/test1488.pl b/tests/test1488.pl
index a8f998845e..1994f93bee 100755
--- a/tests/test1488.pl
+++ b/tests/test1488.pl
@@ -27,6 +27,7 @@
 # a late evening in the #curl IRC channel.
 #
 
+use strict;
 use warnings;
 use vars qw($Cpreprocessor);
 use allversions;
@@ -52,7 +53,7 @@ my $root=$ARGV[0] || ".";
 
 # need an include directory when building out-of-tree
 my $i = ($ARGV[1]) ? "-I$ARGV[1] " : '';
-my $error;
+my $error = 0;
 
 my $versions = $ARGV[2];
 
@@ -60,6 +61,8 @@ my @syms;
 my %manpage;
 my %symadded;
 
+our %pastversion;
+
 sub checkmanpage {
     my ($m) = @_;
 
diff --git a/tests/test1707.pl b/tests/test1707.pl
index d9090d4f9b..249d2914f1 100755
--- a/tests/test1707.pl
+++ b/tests/test1707.pl
@@ -98,7 +98,7 @@ while(<R>) {
 }
 close(R);
 
-my $error;
+my $error = 0;
 if(scalar(@curlout) != scalar(@txtout)) {
     printf "curl -h $opt is %d lines, $txt says %d lines\n",
         scalar(@curlout), scalar(@txtout);
diff --git a/tests/test971.pl b/tests/test971.pl
index 8669145000..b7046ac678 100755
--- a/tests/test971.pl
+++ b/tests/test971.pl
@@ -29,12 +29,19 @@
 #   $cmddir
 #
 
+use strict;
+use warnings;
+
 use allversions;
 
 my $opts = $ARGV[0];
 my $cmddir = $ARGV[1];
 my $versions = $ARGV[2];
 
+my %file;
+my %oiv;
+my $error = 0;
+
 sub cmdfiles {
     my ($dir)=@_;
 
@@ -93,6 +100,8 @@ sub versioncheck {
     close($fh);
 }
 
+our %pastversion;
+
 # get all the past versions
 allversions($versions);
 
diff --git a/tests/testcurl.pl b/tests/testcurl.pl
index 791e366257..8d6183102b 100755
--- a/tests/testcurl.pl
+++ b/tests/testcurl.pl
@@ -61,6 +61,7 @@
 #
 
 use strict;
+use warnings;
 
 use Cwd;
 use File::Spec;
@@ -76,6 +77,9 @@ use vars qw($name $email $desc $confopts $runtestopts $setupfile $mktarball
             $extvercmd $nogitpull $nobuildconf $crosscompile
             $timestamp $notes);
 
+$notes='';
+$runtestopts='';
+
 # version of this script
 $version='2024-11-28';
 $fixed=0;
@@ -338,20 +342,20 @@ logit "DESC = $desc";
 logit "NOTES = $notes";
 logit "CONFOPTS = $confopts";
 logit "RUNTESTOPTS = ".$runtestopts;
-logit "CPPFLAGS = ".$ENV{CPPFLAGS};
-logit "CFLAGS = ".$ENV{CFLAGS};
-logit "LDFLAGS = ".$ENV{LDFLAGS};
-logit "LIBS = ".$ENV{LIBS};
-logit "CC = ".$ENV{CC};
-logit "TMPDIR = ".$ENV{TMPDIR};
-logit "MAKEFLAGS = ".$ENV{MAKEFLAGS};
-logit "ACLOCAL_FLAGS = ".$ENV{ACLOCAL_FLAGS};
-logit "PKG_CONFIG_PATH = ".$ENV{PKG_CONFIG_PATH};
-logit "DYLD_LIBRARY_PATH = ".$ENV{DYLD_LIBRARY_PATH};
-logit "LD_LIBRARY_PATH = ".$ENV{LD_LIBRARY_PATH};
-logit "LIBRARY_PATH = ".$ENV{LIBRARY_PATH};
-logit "SHLIB_PATH = ".$ENV{SHLIB_PATH};
-logit "LIBPATH = ".$ENV{LIBPATH};
+logit "CPPFLAGS = ".($ENV{CPPFLAGS} || '');
+logit "CFLAGS = ".($ENV{CFLAGS} || '');
+logit "LDFLAGS = ".($ENV{LDFLAGS} || '');
+logit "LIBS = ".($ENV{LIBS} || '');
+logit "CC = ".($ENV{CC} || '');
+logit "TMPDIR = ".($ENV{TMPDIR} || '');
+logit "MAKEFLAGS = ".($ENV{MAKEFLAGS} || '');
+logit "ACLOCAL_FLAGS = ".($ENV{ACLOCAL_FLAGS} || '');
+logit "PKG_CONFIG_PATH = ".($ENV{PKG_CONFIG_PATH} || '');
+logit "DYLD_LIBRARY_PATH = ".($ENV{DYLD_LIBRARY_PATH} || '');
+logit "LD_LIBRARY_PATH = ".($ENV{LD_LIBRARY_PATH} || '');
+logit "LIBRARY_PATH = ".($ENV{LIBRARY_PATH} || '');
+logit "SHLIB_PATH = ".($ENV{SHLIB_PATH} || '');
+logit "LIBPATH = ".($ENV{LIBPATH} || '');
 logit "target = ".$targetos;
 logit "version = $version"; # script version
 logit "date = $timestamp";  # When the test build starts