diff --git a/tools/push3-evolution/evolve.sh b/tools/push3-evolution/evolve.sh
index db0067c..8833080 100755
--- a/tools/push3-evolution/evolve.sh
+++ b/tools/push3-evolution/evolve.sh
@@ -834,7 +834,7 @@ for fname in sorted(os.listdir(output_dir)):
                     f'candidate_{int(cand_str):03d}.push3'
                 )
                 if os.path.exists(push3_path):
-                    flags = d.get('fitness_flags', '')
+                    flags = d.get('fitness_flags')
                     qualifying.append((fitness, push3_path, gen_idx, cand_str, flags))
             except (json.JSONDecodeError, ValueError, TypeError, AttributeError):
                 pass