diff --git a/lib/preflight/measurements.rb b/lib/preflight/measurements.rb
index 62acc3b..c7237aa 100644
--- a/lib/preflight/measurements.rb
+++ b/lib/preflight/measurements.rb
@@ -11,13 +11,13 @@ module Measurements
     # convert inches to standard PDF points
     #
     def in2pt(inch)
-      return inch * BigDecimal.new("72")
+      return inch * BigDecimal('72')
     end
 
     # convert mm to standard PDF points
     #
     def mm2pt(mm)
-      return mm * (BigDecimal.new("72") / BigDecimal.new("25.4"))
+      return mm * (BigDecimal('72') / BigDecimal('25.4'))
     end
 
     # convert mm to standard PDF points
diff --git a/lib/preflight/rules/consistent_boxes.rb b/lib/preflight/rules/consistent_boxes.rb
index 403457f..c7fd2c4 100644
--- a/lib/preflight/rules/consistent_boxes.rb
+++ b/lib/preflight/rules/consistent_boxes.rb
@@ -19,7 +19,7 @@ class ConsistentBoxes
 
       # Default tolerance is that each page box MUST be within .03 PDF points
       # of the same box on all other pages
-      DEFAULT_TOLERANCE = (BigDecimal.new("-0.03")..BigDecimal.new("0.03"))
+      DEFAULT_TOLERANCE = (BigDecimal('-0.03')..BigDecimal('0.03'))
 
       attr_reader :issues
 
diff --git a/lib/preflight/rules/cropbox_matches_mediabox.rb b/lib/preflight/rules/cropbox_matches_mediabox.rb
index 7027469..6fbd18e 100644
--- a/lib/preflight/rules/cropbox_matches_mediabox.rb
+++ b/lib/preflight/rules/cropbox_matches_mediabox.rb
@@ -31,7 +31,7 @@ def page=(page)
       private
 
       def round_off(*arr)
-        arr.flatten.compact.map { |n| BigDecimal.new(n.to_s).round(2) }
+        arr.flatten.compact.map { |n| BigDecimal(n.to_s).round(2) }
       end
     end
   end
diff --git a/lib/preflight/rules/mediabox_at_origin.rb b/lib/preflight/rules/mediabox_at_origin.rb
index e241b53..0bf481c 100644
--- a/lib/preflight/rules/mediabox_at_origin.rb
+++ b/lib/preflight/rules/mediabox_at_origin.rb
@@ -35,7 +35,7 @@ def page=(page)
       private
 
       def round_off(*arr)
-        arr.flatten.compact.map { |n| BigDecimal.new(n.to_s).round(2) }
+        arr.flatten.compact.map { |n| BigDecimal(n.to_s).round(2) }
       end
     end
   end
diff --git a/lib/preflight/rules/min_ppi.rb b/lib/preflight/rules/min_ppi.rb
index d9252f7..963301f 100644
--- a/lib/preflight/rules/min_ppi.rb
+++ b/lib/preflight/rules/min_ppi.rb
@@ -65,8 +65,8 @@ def invoke_image_xobject(xobject)
         device_w = pt2in(image_width)
         device_h = pt2in(image_height)
 
-        horizontal_ppi = BigDecimal.new((sample_w / device_w).to_s).round(3)
-        vertical_ppi   = BigDecimal.new((sample_h / device_h).to_s).round(3)
+        horizontal_ppi = BigDecimal((sample_w / device_w).to_s).round(3)
+        vertical_ppi   = BigDecimal((sample_h / device_h).to_s).round(3)
 
         if horizontal_ppi < @min_ppi || vertical_ppi < @min_ppi
           @issues << Issue.new("Image with low PPI/DPI", self, :page           => @page.number,
diff --git a/spec/rules/consistent_boxes_spec.rb b/spec/rules/consistent_boxes_spec.rb
index 8de9056..557b3b7 100644
--- a/spec/rules/consistent_boxes_spec.rb
+++ b/spec/rules/consistent_boxes_spec.rb
@@ -28,7 +28,7 @@
 
   it "pass files with mismatched MediaBox on each page within the defined tolerance" do
     filename  = pdf_spec_file("two_mismatched_pages")
-    tolerance = (BigDecimal.new("-300")..BigDecimal.new("300"))
+    tolerance = (BigDecimal("-300")..BigDecimal("300"))
     rule      = Preflight::Rules::ConsistentBoxes.new(tolerance)
 
     PDF::Reader.open(filename) do |reader|