diff --git a/CHANGELOG.md b/CHANGELOG.md
index c3a28d34..99227c28 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -8,6 +8,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ### Changed
 - metrics registry refactoring to search with `O(1)` [#188](https://github.com/tarantool/metrics/issues/188)
+- `ipairs` instead of `pairs` while iteration in `histogram` [#196](https://github.com/tarantool/metrics/issues/196)
 
 ### Fixed
 - be gentle to http routes, don't leave gaps in the array
diff --git a/metrics/collectors/histogram.lua b/metrics/collectors/histogram.lua
index e575a3c4..6e7bf30a 100644
--- a/metrics/collectors/histogram.lua
+++ b/metrics/collectors/histogram.lua
@@ -9,8 +9,7 @@ local Histogram = Shared:new_class('histogram', {'observe_latency'})
 
 function Histogram.check_buckets(buckets)
     local prev = -math.huge
-    for k, v in pairs(buckets) do
-        if type(k) ~= 'number' then return false end
+    for _, v in ipairs(buckets) do
         if type(v) ~= 'number' then return false end
         if v <= 0 then return false end
         if prev > v then return false end
@@ -48,7 +47,7 @@ function Histogram:observe(num, label_pairs)
     self.count_collector:inc(1, label_pairs)
     self.sum_collector:inc(num, label_pairs)
 
-    for _, bucket in pairs(self.buckets) do
+    for _, bucket in ipairs(self.buckets) do
         local bkt_label_pairs = table.deepcopy(label_pairs)
         bkt_label_pairs.le = bucket
 
@@ -64,13 +63,13 @@ end
 
 function Histogram:collect()
     local result = {}
-    for _, obs in pairs(self.count_collector:collect()) do
+    for _, obs in ipairs(self.count_collector:collect()) do
         table.insert(result, obs)
     end
-    for _, obs in pairs(self.sum_collector:collect()) do
+    for _, obs in ipairs(self.sum_collector:collect()) do
         table.insert(result, obs)
     end
-    for _, obs in pairs(self.bucket_collector:collect()) do
+    for _, obs in ipairs(self.bucket_collector:collect()) do
         table.insert(result, obs)
     end
     return result
diff --git a/test/collectors/histogram_test.lua b/test/collectors/histogram_test.lua
new file mode 100644
index 00000000..6b9e92c8
--- /dev/null
+++ b/test/collectors/histogram_test.lua
@@ -0,0 +1,8 @@
+local t = require('luatest')
+local g = t.group()
+
+local metrics = require('metrics')
+
+g.test_unsorted_buckets_error = function()
+    t.assert_error_msg_contains('Invalid value for buckets', metrics.histogram, 'latency', nil, {0.9, 0.5})
+end