diff --git a/tools/benchcomp/benchcomp/visualizers/__init__.py b/tools/benchcomp/benchcomp/visualizers/__init__.py
index 740ad47b61a8..6c6331dc5e83 100644
--- a/tools/benchcomp/benchcomp/visualizers/__init__.py
+++ b/tools/benchcomp/benchcomp/visualizers/__init__.py
@@ -282,8 +282,8 @@ def _get_variant_names(results):
 
     @staticmethod
     def _compute_scaled_metric(data_for_metric, log_scaling):
-        min_value = None
-        max_value = None
+        min_value = math.inf
+        max_value = -math.inf
         for bench, bench_result in data_for_metric.items():
             for variant, variant_result in bench_result.items():
                 if isinstance(variant_result, (bool, str)):