diff --git a/scripts/flow_counters_stat b/scripts/flow_counters_stat
index 0c2ec80575d9..8901d92f6627 100755
--- a/scripts/flow_counters_stat
+++ b/scripts/flow_counters_stat
@@ -230,7 +230,7 @@ class FlowCounterStats(object):
                     # counter OID is changed.
                     old_values[-1] = values[-1]
                     for i in diff_column_positions:
-                        old_values[i] = 0
+                        old_values[i] = '0'
                         values[i] = ns_diff(values[i], old_values[i])
                     need_update_cache = True
                     continue
@@ -238,13 +238,13 @@ class FlowCounterStats(object):
                 has_negative_diff = False
                 for i in diff_column_positions:
                     # If any diff has negative value, set all counter values to 0 and update cache
-                    if values[i] < old_values[i]:
+                    if int(values[i]) < int(old_values[i]):
                         has_negative_diff = True
                         break
 
                 if has_negative_diff:
                     for i in diff_column_positions:
-                        old_values[i] = 0
+                        old_values[i] = '0'
                         values[i] = ns_diff(values[i], old_values[i])
                     need_update_cache = True
                     continue
diff --git a/tests/flow_counter_stats_test.py b/tests/flow_counter_stats_test.py
index 61c938a06350..807ed6122332 100644
--- a/tests/flow_counter_stats_test.py
+++ b/tests/flow_counter_stats_test.py
@@ -132,25 +132,25 @@ def test_diff(self):
         stats._collect = mock.MagicMock()
         old_data = {
             '': {
-                'bgp': [100, 200, 50.0, 1],
-                'bgpv6': [100, 200, 50.0, 2],
-                'lldp': [100, 200, 50.0, 3],
+                'bgp': ['100', '200', '50.0', '1'],
+                'bgpv6': ['100', '200', '50.0', '2'],
+                'lldp': ['100', '200', '50.0', '3'],
             }
         }
         stats._save(old_data)
         stats.data = {
             '': {
-                'bgp': [100, 200, 50.0, 4],
-                'bgpv6': [100, 100, 50.0, 2],
-                'lldp': [200, 300, 50.0, 3],
+                'bgp': ['100', '200', '50.0', '4'],
+                'bgpv6': ['100', '100', '50.0', '2'],
+                'lldp': ['200', '300', '50.0', '3'],
             }
         }
 
         stats._collect_and_diff()
         cached_data = stats._load()
-        assert cached_data['']['bgp'] == [0, 0, 50.0, 4]
-        assert cached_data['']['bgpv6'] == [0, 0, 50.0, 2]
-        assert cached_data['']['lldp'] == [100, 200, 50.0, 3]
+        assert cached_data['']['bgp'] == ['0', '0', '50.0', '4']
+        assert cached_data['']['bgpv6'] == ['0', '0', '50.0', '2']
+        assert cached_data['']['lldp'] == ['100', '200', '50.0', '3']
 
 
 class TestTrapStatsMultiAsic: