diff --git a/.rubocop.yml b/.rubocop.yml
index 8b5a17f71f..1e307d7184 100644
--- a/.rubocop.yml
+++ b/.rubocop.yml
@@ -1,6 +1,7 @@
 inherit_from: .rubocop_todo.yml
 
 plugins:
+  - rubocop-performance
   - rubocop-rake
   - rubocop-rspec
 
diff --git a/Gemfile b/Gemfile
index 36d9253e5f..5ecf555c7f 100644
--- a/Gemfile
+++ b/Gemfile
@@ -20,6 +20,7 @@ gem "rake"
 
 # Linting
 gem "rubocop", require: false
+gem "rubocop-performance", require: false
 gem "rubocop-rake", require: false
 gem "rubocop-rspec", require: false
 
diff --git a/spec/money/allocation_spec.rb b/spec/money/allocation_spec.rb
index eda4ca54c6..264a27ced0 100644
--- a/spec/money/allocation_spec.rb
+++ b/spec/money/allocation_spec.rb
@@ -56,7 +56,7 @@
             BigDecimal("33.3333333333"),
           ],
         )
-        expect(parts.inject(0, :+)).to eq(amount)
+        expect(parts.sum).to eq(amount)
       end
     end
   end
@@ -132,7 +132,7 @@
             BigDecimal("33.3333333333"),
           ],
         )
-        expect(parts.inject(0, :+)).to eq(amount)
+        expect(parts.sum).to eq(amount)
       end
     end
   end
@@ -156,7 +156,7 @@
       ]
 
       result = described_class.generate(amount, allocations)
-      expect(result.reduce(&:+)).to eq(amount)
+      expect(result.sum).to eq(amount)
       expect(result).to eq(
         [
           61566,
@@ -193,7 +193,7 @@
       ]
 
       result = described_class.generate(amount, allocations)
-      expect(result.reduce(&:+)).to eq(amount)
+      expect(result.sum).to eq(amount)
       expect(result).to eq(
         [
           -61566,
@@ -229,7 +229,7 @@
 
       it "allocates with required precision" do
         result = described_class.generate(amount, allocations, 16)
-        expect(result.reduce(&:+)).to eq(amount)
+        expect(result.sum).to eq(amount)
 
         expected = %w[
           6.3347130857200688 6.3347130857200689 6.3347130857200688 6.3347130857200688
diff --git a/spec/money/currency_spec.rb b/spec/money/currency_spec.rb
index 04da83328d..6252fc2b91 100644
--- a/spec/money/currency_spec.rb
+++ b/spec/money/currency_spec.rb
@@ -310,7 +310,7 @@ def to_s
 
     it "is thread safe" do
       ids = []
-      2.times.map { Thread.new { ids << described_class.new("USD").object_id } }.each(&:join)
+      Array.new(2) { Thread.new { ids << described_class.new("USD").object_id } }.each(&:join)
       expect(ids.uniq.length).to eq(1)
     end
   end
diff --git a/spec/money/rates_store/memory_spec.rb b/spec/money/rates_store/memory_spec.rb
index 3b0b6d98d2..abd98bf902 100644
--- a/spec/money/rates_store/memory_spec.rb
+++ b/spec/money/rates_store/memory_spec.rb
@@ -42,7 +42,7 @@
   end
 
   describe "#transaction" do
-    let(:guard) { store.instance_variable_get("@guard") }
+    let(:guard) { store.instance_variable_get(:@guard) }
 
     before do
       allow(guard).to receive(:synchronize)
diff --git a/spec/money_spec.rb b/spec/money_spec.rb
index c079d702e4..02dc61f293 100644
--- a/spec/money_spec.rb
+++ b/spec/money_spec.rb
@@ -889,7 +889,7 @@
     end
 
     it "does not round rationals" do
-      splits = 7.times.map { Rational(950, 6650) }
+      splits = Array.new(7) { Rational(950, 6650) }
       moneys = Money.us_dollar(6650).allocate(splits)
       moneys.each do |money|
         expect(money.cents).to eq 950
@@ -937,7 +937,7 @@
     context "with infinite_precision", :default_infinite_precision_true do
       it "allows for fractional cents allocation" do
         moneys = Money.new(100).allocate([1, 1, 1])
-        expect(moneys.inject(0, :+)).to eq(Money.new(100))
+        expect(moneys.sum).to eq(Money.new(100))
       end
     end
   end
@@ -975,7 +975,7 @@
     context "with infinite_precision", :default_infinite_precision_true do
       it "allows for splitting by fractional cents" do
         moneys = Money.new(100).split(3)
-        expect(moneys.inject(0, :+)).to eq(Money.new(100))
+        expect(moneys.sum).to eq(Money.new(100))
       end
     end
   end