diff --git a/kpi/models/kpi_threshold.py b/kpi/models/kpi_threshold.py
index 07cab10e1..7e00023d1 100644
--- a/kpi/models/kpi_threshold.py
+++ b/kpi/models/kpi_threshold.py
@@ -13,15 +13,19 @@ class KPIThreshold(models.Model):
 
     @api.multi
     def _compute_is_valid_threshold(self):
-        result = {}
         for obj in self:
             # check if ranges overlap
             # TODO: This code can be done better
+            obj.valid = True
             for range1 in obj.range_ids:
-                for range2 in obj.range_ids:
-                    if (range1.valid and range2.valid and
-                            range1.min_value < range2.min_value):
-                        obj.valid = range1.max_value <= range2.min_value
+                if not range1.valid:
+                    obj.valid = False
+                    break
+                for range2 in (obj.range_ids-range1):
+                    if (range1.max_value >= range2.min_value and
+                            range1.min_value <= range2.max_value):
+                        obj.valid = False
+                        break
             if obj.valid:
                 obj.invalid_message = None
             else:
diff --git a/kpi/models/kpi_threshold_range.py b/kpi/models/kpi_threshold_range.py
index c637cc9bf..43e2b2f13 100644
--- a/kpi/models/kpi_threshold_range.py
+++ b/kpi/models/kpi_threshold_range.py
@@ -95,7 +95,6 @@ class KPIThresholdRange(models.Model):
 
     @api.multi
     def _compute_min_value(self):
-        result = {}
         for obj in self:
             value = None
             error = None
@@ -121,11 +120,9 @@ class KPIThresholdRange(models.Model):
                 error = str(e)
             obj.min_value = value
             obj.min_error = error
-        return result
 
     @api.multi
     def _compute_max_value(self):
-        result = {}
         for obj in self:
             value = None
             error = None
@@ -151,11 +148,9 @@ class KPIThresholdRange(models.Model):
                 error = str(e)
             obj.max_value = value
             obj.max_error = error
-        return result
 
     @api.multi
     def _compute_is_valid_range(self):
-        result = {}
         for obj in self:
             if obj.min_error or obj.max_error:
                 obj.valid = False
@@ -170,5 +165,4 @@ class KPIThresholdRange(models.Model):
             else:
                 obj.valid = True
                 obj.invalid_message = ""
-        return result