diff --git a/Gemfile.lock b/Gemfile.lock
index 15291aa..f2b3c77 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -1,7 +1,7 @@
 PATH
   remote: .
   specs:
-    statisfy (0.0.9)
+    statisfy (0.0.10)
 
 GEM
   remote: https://rubygems.org/
diff --git a/lib/statisfy/monthly.rb b/lib/statisfy/monthly.rb
index 78e1460..32e61a5 100644
--- a/lib/statisfy/monthly.rb
+++ b/lib/statisfy/monthly.rb
@@ -22,7 +22,7 @@ def values_grouped_by_month(scope: nil, start_at: nil, stop_at: nil)
 
         if start_at.present? || scope&.created_at.present?
           start_at ||= scope.created_at
-          n_months = (Time.zone.today.year + Time.zone.today.month) - (start_at.year + start_at.month)
+          n_months = (Time.zone.today.year * 12 + Time.zone.today.month) - (start_at.year * 12 + start_at.month)
         end
 
         relevant_months = (0..n_months).map do |i|
diff --git a/statisfy-0.0.3.gem b/statisfy-0.0.3.gem
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diff --git a/statisfy-0.0.5.gem b/statisfy-0.0.5.gem
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diff --git a/statisfy-0.0.6.gem b/statisfy-0.0.6.gem
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diff --git a/statisfy-0.0.7.gem b/statisfy-0.0.7.gem
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diff --git a/statisfy-0.0.8.gem b/statisfy-0.0.8.gem
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diff --git a/statisfy-0.0.9.gem b/statisfy-0.0.9.gem
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diff --git a/statisfy.gemspec b/statisfy.gemspec
index 18b2232..3fb58d6 100644
--- a/statisfy.gemspec
+++ b/statisfy.gemspec
@@ -2,7 +2,7 @@
 
 Gem::Specification.new do |s|
   s.name        = "statisfy"
-  s.version     = "0.0.9"
+  s.version     = "0.0.10"
   s.required_ruby_version = ">= 3.2.0"
   s.date        = "2023-12-13"
   s.summary     = "A performant and flexible counter solution"