diff --git a/src/lib/Hydra/Helper/AddBuilds.pm b/src/lib/Hydra/Helper/AddBuilds.pm
index d608e085..37061425 100644
--- a/src/lib/Hydra/Helper/AddBuilds.pm
+++ b/src/lib/Hydra/Helper/AddBuilds.pm
@@ -56,7 +56,7 @@ sub updateDeclarativeJobset {
             $input->jobsetinputalts->create({altnr => 0, value => $data->{value}});
         }
         delete $declSpec->{"inputs"};
-        die "invalid keys in declarative specification file\n" if (%{$declSpec});
+        die "invalid keys ($declSpec) in declarative specification file\n" if (%{$declSpec});
     });
 };
 
diff --git a/src/lib/Hydra/Helper/Nix.pm b/src/lib/Hydra/Helper/Nix.pm
index 07f266e3..8ce284ad 100644
--- a/src/lib/Hydra/Helper/Nix.pm
+++ b/src/lib/Hydra/Helper/Nix.pm
@@ -425,7 +425,13 @@ sub run {
 sub grab {
     my (%args) = @_;
     my $res = run(%args, grabStderr => 0);
-    die "command `@{$args{cmd}}' failed with exit status $res->{status}" if $res->{status};
+    if ($res->{status}) {
+        my $msgloc = "(in an indeterminate location)";
+        if (defined $args{dir}) {
+            $msgloc = "in $args{dir}";
+        }
+        die "command `@{$args{cmd}}' failed with exit status $res->{status} $msgloc";
+    }
     return $res->{stdout};
 }