diff --git a/pkgs/top-level/metrics.nix b/pkgs/top-level/metrics.nix
index c6380b74a667..574e8f510a8b 100644
--- a/pkgs/top-level/metrics.nix
+++ b/pkgs/top-level/metrics.nix
@@ -93,7 +93,7 @@ stdenvNoCC.mkDerivation {
     # It's slightly unclear which of the set to track: qaCount, qaCountDrv, qaCountBroken.
     num="$(wc -l < metrics/nix-env.qa/output)"
     echo "nix-env.qaCount $num" >> hydra-metrics
-    qaCountDrv="$(jq -r 'reduce .[].drvPath as $d (0; .+1)' metrics/nix-env.qaDrv/output)"
+    qaCountDrv="$(jq -r 'reduce (.[].drvPath? // empty) as $d (0; .+1)' metrics/nix-env.qaDrv/output)"
     numBroken="$((num - $qaCountDrv))"
     echo "nix-env.qaCountBroken $numBroken" >> hydra-metrics