diff --git a/src/tools/copyright.pl b/src/tools/copyright.pl
index 804537f26a..5dd63b2ce1 100755
--- a/src/tools/copyright.pl
+++ b/src/tools/copyright.pl
@@ -44,7 +44,7 @@ sub wanted
 	return if ($_ =~ m/\.(ico|bin|po|key)$/);
 
 	my @lines;
-	tie @lines, "Tie::File", $File::Find::name;
+	tie @lines, 'Tie::File', $File::Find::name;
 
 	# We process all lines because some files have copyright
 	# strings embedded in them, e.g. src/bin/psql/help.c
diff --git a/src/tools/gen_export.pl b/src/tools/gen_export.pl
index d9fdaaaf6d..eca43fa1f2 100644
--- a/src/tools/gen_export.pl
+++ b/src/tools/gen_export.pl
@@ -14,7 +14,7 @@ GetOptions(
 	'format:s' => \$format,
 	'libname:s' => \$libname,
 	'input:s' => \$input,
-	'output:s' => \$output) or die "wrong arguments";
+	'output:s' => \$output) or die 'wrong arguments';
 
 if (not(   $format eq 'darwin'
 		or $format eq 'gnu'
@@ -32,9 +32,9 @@ open(my $output_handle, '>', $output)
 
 if ($format eq 'gnu')
 {
-	print $output_handle "{
+	print $output_handle '{
   global:
-";
+';
 }
 elsif ($format eq 'win')
 {
@@ -76,7 +76,7 @@ while (<$input_handle>)
 
 if ($format eq 'gnu')
 {
-	print $output_handle "  local: *;
+	print $output_handle '  local: *;
 };
-";
+';
 }
diff --git a/src/tools/gen_keywordlist.pl b/src/tools/gen_keywordlist.pl
index 1b3bc2e9b4..22e65f3197 100644
--- a/src/tools/gen_keywordlist.pl
+++ b/src/tools/gen_keywordlist.pl
@@ -160,7 +160,7 @@ printf $kwdef "#define %s_NUM_KEYWORDS %d\n\n", uc $varname, scalar @keywords;
 
 # Emit the definition of the hash function.
 
-my $funcname = $varname . "_hash_func";
+my $funcname = $varname . '_hash_func';
 
 my $f = PerfectHash::generate_hash_function(\@keywords, $funcname,
 	case_fold => $case_fold);
@@ -169,7 +169,7 @@ printf $kwdef qq|static %s\n|, $f;
 
 # Emit the struct that wraps all this lookup info into one variable.
 
-printf $kwdef "static " if !$extern;
+printf $kwdef 'static ' if !$extern;
 printf $kwdef "const ScanKeywordList %s = {\n", $varname;
 printf $kwdef qq|\t%s_kw_string,\n|, $varname;
 printf $kwdef qq|\t%s_kw_offsets,\n|, $varname;
diff --git a/src/tools/msvc_gendef.pl b/src/tools/msvc_gendef.pl
index 97346cc892..9c115c1ca5 100644
--- a/src/tools/msvc_gendef.pl
+++ b/src/tools/msvc_gendef.pl
@@ -72,10 +72,10 @@ sub extract_syms
 		next unless $pieces[6];
 
 		# Skip externs used from another compilation unit
-		next if ($pieces[2] eq "UNDEF");
+		next if ($pieces[2] eq 'UNDEF');
 
 		# Skip static symbols
-		next unless ($pieces[4] eq "External");
+		next unless ($pieces[4] eq 'External');
 
 		# Skip some more MSVC-generated crud
 		next if $pieces[6] =~ /^@/;
@@ -120,7 +120,7 @@ sub writedef
 
 		# Strip the leading underscore for win32, but not x64
 		$f =~ s/^_//
-		  unless ($arch eq "x86_64");
+		  unless ($arch eq 'x86_64');
 
 		# Emit just the name if it's a function symbol, or emit the name
 		# decorated with the DATA option for variables.
@@ -193,11 +193,11 @@ mkdir($tempdir) unless -d $tempdir;
 
 my $cmd = "dumpbin /nologo /symbols /out:$tmpfile " . join(' ', @files);
 
-system($cmd) == 0 or die "Could not call dumpbin";
+system($cmd) == 0 or die 'Could not call dumpbin';
 rename($tmpfile, $symfile) or die $!;
 extract_syms($symfile, \%def);
 print "\n";
 
 writedef($deffile, $arch, \%def);
 
-print "Generated " . scalar(keys(%def)) . " symbols\n";
+print 'Generated ' . scalar(keys(%def)) . " symbols\n";
diff --git a/src/tools/version_stamp.pl b/src/tools/version_stamp.pl
index 3743ece299..1b15d73a86 100755
--- a/src/tools/version_stamp.pl
+++ b/src/tools/version_stamp.pl
@@ -37,7 +37,7 @@ if ($minor =~ m/^\d+$/)
 {
 	$dotneeded = 1;
 }
-elsif ($minor eq "devel")
+elsif ($minor eq 'devel')
 {
 	$dotneeded = 0;
 }
@@ -63,7 +63,7 @@ my $fullversion;
 # Create various required forms of the version number
 if ($dotneeded)
 {
-	$fullversion = $majorversion . "." . $minor;
+	$fullversion = $majorversion . '.' . $minor;
 }
 else
 {
@@ -73,8 +73,8 @@ else
 # Get the autoconf version number for eventual nag message
 # (this also ensures we're in the right directory)
 
-my $aconfver = "";
-open(my $fh, '<', "configure.ac") || die "could not read configure.ac: $!\n";
+my $aconfver = '';
+open(my $fh, '<', 'configure.ac') || die "could not read configure.ac: $!\n";
 while (<$fh>)
 {
 	if (m/^m4_if\(m4_defn\(\[m4_PACKAGE_VERSION\]\), \[(.*)\], \[\], \[m4_fatal/
@@ -85,17 +85,17 @@ while (<$fh>)
 	}
 }
 close($fh);
-$aconfver ne ""
+$aconfver ne ''
   || die "could not find autoconf version number in configure.ac\n";
 
 # Update configure.ac and other files that contain version numbers
 
-my $fixedfiles = "";
+my $fixedfiles = '';
 
-sed_file("configure.ac",
+sed_file('configure.ac',
 	"-e 's/AC_INIT(\\[PostgreSQL\\], \\[[0-9a-z.]*\\]/AC_INIT([PostgreSQL], [$fullversion]/'"
 );
-sed_file("meson.build",
+sed_file('meson.build',
 	qq{-e "/^project(/,/^)/ s/ version: '[0-9a-z.]*',/ version: '$fullversion',/"}
 );
 
@@ -107,7 +107,7 @@ exit 0;
 sub sed_file
 {
 	my ($filename, $sedargs) = @_;
-	my ($tmpfilename) = $filename . ".tmp";
+	my ($tmpfilename) = $filename . '.tmp';
 
 	system("sed $sedargs $filename >$tmpfilename") == 0
 	  or die "sed failed: $?";
diff --git a/src/tools/win32tzlist.pl b/src/tools/win32tzlist.pl
index 17d45b9570..e0896e934a 100755
--- a/src/tools/win32tzlist.pl
+++ b/src/tools/win32tzlist.pl
@@ -38,7 +38,7 @@ my $tzfile = 'src/bin/initdb/findtimezone.c';
 #
 my $basekey;
 $HKEY_LOCAL_MACHINE->Open(
-	"SOFTWARE\\Microsoft\\Windows NT\\CurrentVersion\\Time Zones", $basekey)
+	'SOFTWARE\\Microsoft\\Windows NT\\CurrentVersion\\Time Zones', $basekey)
   or die $!;
 
 my @subkeys;