diff --git a/doc-src/HAML_CHANGELOG.md b/doc-src/HAML_CHANGELOG.md
index c309c903..cb827b00 100644
--- a/doc-src/HAML_CHANGELOG.md
+++ b/doc-src/HAML_CHANGELOG.md
@@ -10,6 +10,10 @@
 
 * Don't throw errors when text is nested within comments.
 
+* Fix html2haml.
+
+* Fix an issue where destructive modification was sometimes performed on Rails SafeBuffers.
+
 ## 3.1.1
 
 * Update the vendored Sass to version 3.1.0.
diff --git a/lib/haml/compiler.rb b/lib/haml/compiler.rb
index c742a40b..0cfc4179 100644
--- a/lib/haml/compiler.rb
+++ b/lib/haml/compiler.rb
@@ -379,7 +379,7 @@ END
         value = Haml::Helpers.preserve(escaped)
         if escape_attrs
           # We want to decide whether or not to escape quotes
-          value.gsub!('"', '"')
+          value = value.gsub('"', '"')
           this_attr_wrapper = attr_wrapper
           if value.include? attr_wrapper
             if value.include? other_quote_char
diff --git a/lib/haml/exec.rb b/lib/haml/exec.rb
index 81eea019..fc8b6217 100644
--- a/lib/haml/exec.rb
+++ b/lib/haml/exec.rb
@@ -9,7 +9,7 @@ module Haml
       # @param args [Array<String>] The command-line arguments
       def initialize(args)
         @args = args
-        @options = {}
+        @options = {:for_engine => {}}
       end
 
       # Parses the command-line arguments and runs the executable.
diff --git a/lib/haml/helpers.rb b/lib/haml/helpers.rb
index ec527cde..74896f39 100644
--- a/lib/haml/helpers.rb
+++ b/lib/haml/helpers.rb
@@ -107,7 +107,9 @@ MESSAGE
     #   @yield The block within which to escape newlines
     def find_and_preserve(input = nil, tags = haml_buffer.options[:preserve], &block)
       return find_and_preserve(capture_haml(&block), input || tags) if block
-      input.to_s.gsub(/<(#{tags.map(&Regexp.method(:escape)).join('|')})([^>]*)>(.*?)(<\/\1>)/im) do
+      re = /<(#{tags.map(&Regexp.method(:escape)).join('|')})([^>]*)>(.*?)(<\/\1>)/im
+      input.to_s.gsub(re) do |s|
+        s =~ re # Can't rely on $1, etc. existing since Rails' SafeBuffer#gsub is incompatible
         "<#{$1}#{$2}>#{preserve($3)}</#{$1}>"
       end
     end
@@ -170,10 +172,10 @@ MESSAGE
         result = capture_haml(i, &block)
 
         if result.count("\n") > 1
-          result.gsub!("\n", "\n  ")
+          result = result.gsub("\n", "\n  ")
           result = "\n  #{result.strip}\n"
         else
-          result.strip!
+          result = result.strip
         end
 
         "<li>#{result}</li>"