diff --git a/src/lib/Hydra/Helper/Nix.pm b/src/lib/Hydra/Helper/Nix.pm
index e1c56b06..063e053e 100644
--- a/src/lib/Hydra/Helper/Nix.pm
+++ b/src/lib/Hydra/Helper/Nix.pm
@@ -306,7 +306,8 @@ sub getEvals {
             { order_by => "id DESC", rows => 1 });
 
         my $curInfo = getEvalInfo($cache, $curEval);
-        my $prevInfo = getEvalInfo($cache, $prevEval) if defined $prevEval;
+        my $prevInfo;
+        $prevInfo = getEvalInfo($cache, $prevEval) if defined $prevEval;
 
         # Compute what inputs changed between each eval.
         my @changedInputs;
diff --git a/src/lib/Hydra/Plugin/CoverityScan.pm b/src/lib/Hydra/Plugin/CoverityScan.pm
index fcedf92a..472b8e7e 100644
--- a/src/lib/Hydra/Plugin/CoverityScan.pm
+++ b/src/lib/Hydra/Plugin/CoverityScan.pm
@@ -82,7 +82,8 @@ sub buildFinished {
     my $versionRE = "(?:[A-Za-z0-9\.\-]+)";
 
     my $shortName = basename($covTarball);
-    my $version = $2 if $shortName =~ /^($pkgNameRE)-($versionRE)-coverity-int.*$/;
+    my $version;
+    $version = $2 if $shortName =~ /^($pkgNameRE)-($versionRE)-coverity-int.*$/;
 
     die "CoverityScan.pm: Couldn't parse build version for upload! ($shortName)"
         unless defined $version;
diff --git a/src/script/hydra-eval-jobset b/src/script/hydra-eval-jobset
index cca2243d..4a165d86 100755
--- a/src/script/hydra-eval-jobset
+++ b/src/script/hydra-eval-jobset
@@ -122,7 +122,8 @@ sub fetchInputBuild {
     my $versionRE = "(?:[A-Za-z0-9\.\-]+)";
 
     my $relName = ($prevBuild->releasename or $prevBuild->nixname);
-    my $version = $2 if $relName =~ /^($pkgNameRE)-($versionRE)$/;
+    my $version;
+    $version = $2 if $relName =~ /^($pkgNameRE)-($versionRE)$/;
 
     my $mainOutput = getMainOutput($prevBuild);
 
@@ -167,7 +168,8 @@ sub fetchInputSystemBuild {
         my $versionRE = "(?:[A-Za-z0-9\.\-]+)";
 
         my $relName = ($prevBuild->releasename or $prevBuild->nixname);
-        my $version = $2 if $relName =~ /^($pkgNameRE)-($versionRE)$/;
+        my $version;
+        $version = $2 if $relName =~ /^($pkgNameRE)-($versionRE)$/;
 
         my $input =
             { storePath => getMainOutput($prevBuild)->path