diff --git a/ivtmetrics/recognition.py b/ivtmetrics/recognition.py
index c785bf1..9320543 100755
--- a/ivtmetrics/recognition.py
+++ b/ivtmetrics/recognition.py
@@ -60,10 +60,7 @@ def __init__(self, num_class=100, ignore_null=False):
         self.reset_global()   
 
     def resolve_nan(self, classwise):
-        equiv_nan = ['-0', '-0.', '-0.0', '-.0']
-        classwise = list(map(str, classwise))
-        classwise = [np.nan if x in equiv_nan else x for x in classwise]
-        classwise = np.array(list(map(float, classwise)))
+        classwise[classwise==-0.0] = np.nan
         return classwise
         
     ##%%%%%%%%%%%%%%%%%%% RESET OP #%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
@@ -264,4 +261,4 @@ def aggregate_global_records_partial(self):
         if len(self.targets) > 0:
             global_targets.append(self.targets)
             global_predictions.append(self.predictions)
-        return global_targets, global_predictions
\ No newline at end of file
+        return global_targets, global_predictions