diff --git a/Library/Homebrew/dev-cmd/bump-formula-pr.rb b/Library/Homebrew/dev-cmd/bump-formula-pr.rb
index e45aa9398d..c4aef20b2b 100644
--- a/Library/Homebrew/dev-cmd/bump-formula-pr.rb
+++ b/Library/Homebrew/dev-cmd/bump-formula-pr.rb
@@ -15,6 +15,39 @@
 require "formula"
 
 module Homebrew
+  def inreplace_pairs(path, replacement_pairs)
+    if ARGV.dry_run?
+      contents = path.open("r") { |f| Formulary.set_encoding(f).read }
+      contents.extend(StringInreplaceExtension)
+      replacement_pairs.each do |old, new|
+        ohai "replace \"#{old}\" with \"#{new}\"" unless ARGV.flag?("--quiet")
+        contents.gsub!(old, new)
+      end
+      if contents.errors.any?
+        raise Utils::InreplaceError, path => contents.errors
+      end
+      contents
+    else
+      Utils::Inreplace.inreplace(path) do |s|
+        replacement_pairs.each do |old, new|
+          ohai "replace \"#{old}\" with \"#{new}\"" unless ARGV.flag?("--quiet")
+          s.gsub!(old, new)
+        end
+      end
+      path.open("r") { |f| Formulary.set_encoding(f).read }
+    end
+  end
+
+  def formula_version(formula, spec, contents = nil)
+    name = formula.name
+    path = formula.path
+    if contents
+      Formulary.from_contents(name, path, contents, spec).version
+    else
+      Formulary::FormulaLoader.new(name, path).get_formula(spec).version
+    end
+  end
+
   def bump_formula_pr
     formula = ARGV.formulae.first
     odie "No formula found!" unless formula
@@ -51,32 +84,35 @@ module Homebrew
       safe_system "brew", "update"
     end
 
-    Utils::Inreplace.inreplace(formula.path) do |s|
-      if new_url_hash
-        old_url = formula_spec.url
-        if ARGV.dry_run?
-          ohai "replace '#{old_url}' with '#{new_url}'"
-          ohai "replace '#{old_hash}' with '#{new_hash}'"
-        else
-          s.gsub!(old_url, new_url)
-          s.gsub!(old_hash, new_hash)
-        end
-      else
-        resource_specs = formula_spec.specs
-        old_tag = resource_specs[:tag]
-        old_revision = resource_specs[:revision]
-        if ARGV.dry_run?
-          ohai "replace '#{old_tag}' with '#{new_tag}'"
-          ohai "replace '#{old_revision}' with '#{new_revision}'"
-        else
-          s.gsub!(/['"]#{old_tag}['"]/, "\"#{new_tag}\"")
-          s.gsub!(old_revision, new_revision)
-        end
-      end
+    old_formula_version = formula_version(formula, requested_spec)
+
+    replacement_pairs = if new_url_hash
+      [
+        [formula_spec.url, new_url],
+        [old_hash, new_hash],
+      ]
+    else
+      [
+        [formula_spec.specs[:tag], new_tag],
+        [formula_spec.specs[:revision], new_revision],
+      ]
     end
 
-    new_formula = Formulary.load_formula_from_path(formula.name, formula.path)
-    new_formula_version = new_formula.version
+    new_contents = inreplace_pairs(formula.path, replacement_pairs)
+
+    new_formula_version = formula_version(formula, requested_spec, new_contents)
+
+    if new_formula_version < old_formula_version
+      odie <<-EOS.undent
+        You probably need to bump this formula manually since changing the
+        version from #{old_formula_version} to #{new_formula_version} would be a downgrade.
+      EOS
+    elsif new_formula_version == old_formula_version
+      odie <<-EOS.undent
+        You probably need to bump this formula manually since the new version
+        and old version are both #{new_formula_version}.
+      EOS
+    end
 
     unless Formula["hub"].any_version_installed?
       if ARGV.dry_run?