diff --git a/Math/Topology/MetricsND.php b/Math/Topology/MetricsND.php
index edfe9be36..4c27d6a55 100644
--- a/Math/Topology/MetricsND.php
+++ b/Math/Topology/MetricsND.php
@@ -112,7 +112,7 @@ final class MetricsND
             $dist[] = \abs($a[$key] - $b[$key]);
         }
 
-        return \max($dist);
+        return (float) \max($dist);
     }
 
     /**