diff --git a/.rubocop.yml b/.rubocop.yml
index d1b1b7baf..dc3ef6fc0 100644
--- a/.rubocop.yml
+++ b/.rubocop.yml
@@ -941,7 +941,7 @@ Style/For:
   Enabled: true
 
 Style/FormatString:
-  Enabled: false
+  Enabled: true
 
 Style/FormatStringToken:
   Enabled: true
diff --git a/app/controllers/stats_controller.rb b/app/controllers/stats_controller.rb
index 2f6b5b3a8..d37af55f4 100644
--- a/app/controllers/stats_controller.rb
+++ b/app/controllers/stats_controller.rb
@@ -93,7 +93,7 @@ class StatsController < ApplicationController
     else
       evolution = 0
     end
-    formatted_evolution = sprintf("%+d", evolution)
+    formatted_evolution = format("%+d", evolution)
 
     {
       total: total.to_s,
@@ -111,7 +111,7 @@ class StatsController < ApplicationController
     else
       evolution = 0
     end
-    formatted_evolution = sprintf("%+d", evolution)
+    formatted_evolution = format("%+d", evolution)
 
     {
       total: total.to_s,
diff --git a/lib/tasks/task_helper.rb b/lib/tasks/task_helper.rb
index 04ef5d32b..7443af5ff 100644
--- a/lib/tasks/task_helper.rb
+++ b/lib/tasks/task_helper.rb
@@ -52,7 +52,7 @@ class ProgressReport
 
   def print_progress
     elapsed = Time.zone.now - @start
-    percent = sprintf('%5.1f%%', @per_10_000 / 100.0)
+    percent = format('%5.1f%%', @per_10_000 / 100.0)
     total = @total.to_s
     count = @count.to_s.rjust(total.length)
     rake_print("\r#{percent} (#{count}/#{total}) [#{format_duration(elapsed)}/#{format_duration(elapsed * 10_000.0 / @per_10_000)}]")