diff --git a/src/lib/Hydra/Helper/Nix.pm b/src/lib/Hydra/Helper/Nix.pm
index 063e053e..e76ac18b 100644
--- a/src/lib/Hydra/Helper/Nix.pm
+++ b/src/lib/Hydra/Helper/Nix.pm
@@ -343,11 +343,11 @@ sub getMachines {
     for my $machinesFile (@machinesFiles) {
         next unless -e $machinesFile;
         open my $conf, "<$machinesFile" or die;
-        while (<$conf>) {
+        while (my $line = <$conf>) {
             chomp;
             s/\#.*$//g;
             next if /^\s*$/;
-            my @tokens = split /\s/, $_;
+            my @tokens = split /\s/, $line;
             my @supportedFeatures = split(/,/, $tokens[5] || "");
             my @mandatoryFeatures = split(/,/, $tokens[6] || "");
             $machines{$tokens[0]} =
diff --git a/src/lib/Hydra/Plugin/CoverityScan.pm b/src/lib/Hydra/Plugin/CoverityScan.pm
index 472b8e7e..c7b39d02 100644
--- a/src/lib/Hydra/Plugin/CoverityScan.pm
+++ b/src/lib/Hydra/Plugin/CoverityScan.pm
@@ -53,9 +53,9 @@ sub buildFinished {
     my $covTarball;
 
     opendir my $tarballs_handle, $tarballs or die;
-    while (readdir $tarballshandle) {
-        next unless $_ =~ /.*-coverity-int\.(tgz|lzma|xz|bz2|zip)$/;
-        $covTarball = "$tarballs/$_"; last;
+    while (my $file = readdir $tarballshandle) {
+        next unless $file =~ /.*-coverity-int\.(tgz|lzma|xz|bz2|zip)$/;
+        $covTarball = "$tarballs/$file"; last;
     }
     closedir $tarballs_handle;
 
diff --git a/src/lib/Hydra/Plugin/SoTest.pm b/src/lib/Hydra/Plugin/SoTest.pm
index e3abf4cc..5b45f153 100644
--- a/src/lib/Hydra/Plugin/SoTest.pm
+++ b/src/lib/Hydra/Plugin/SoTest.pm
@@ -102,8 +102,8 @@ sub buildFinished {
     open( $authfile, "<", $sotest->{authfile} )
       or die "Cannot open Sotest authfile \${\$sotest->{authfile}}";
 
-    while (<$authfile>) {
-        if ( $_ =~ /(.+):(.+)/m ) {
+    while (my $line = <$authfile>) {
+        if ( $line =~ /(.+):(.+)/m ) {
             $sotest_username = $1;
             $sotest_password = $2;
         }
diff --git a/t/s3-backup-test.pl b/t/s3-backup-test.pl
index 825162d3..9332ab15 100644
--- a/t/s3-backup-test.pl
+++ b/t/s3-backup-test.pl
@@ -40,9 +40,9 @@ ok(-e "/tmp/s3/hydra/$successful_hash.narinfo", "The narinfo of a build that's a
 
 my $gcRootsDir = getGCRootsDir;
 opendir my $dir, $gcRootsDir or die;
-while(readdir $dir) {
-    next if $_ eq "." or $_ eq "..";
-    unlink "$gcRootsDir/$_";
+while(my $file = readdir $dir) {
+    next if $file eq "." or $file eq "..";
+    unlink "$gcRootsDir/$file";
 }
 closedir $dir;
 system("hydra-s3-backup-collect-garbage");