diff --git a/lib/docx_replace.rb b/lib/docx_replace.rb
index 0e702df..a7d9795 100644
--- a/lib/docx_replace.rb
+++ b/lib/docx_replace.rb
@@ -6,25 +6,28 @@
 
 module DocxReplace
   class Doc
-    attr_reader :document_content
+    attr_reader :document_contents
 
     def initialize(path, temp_dir=nil)
       @zip_file = Zip::File.new(path)
+      @document_file_paths = find_query_file_paths()
       @temp_dir = temp_dir
-      read_docx_file
+      read_docx_files
     end
 
     def replace(pattern, replacement, multiple_occurrences=false)
       replace = replacement.to_s.encode(xml: :text)
-      if multiple_occurrences
-        @document_content.force_encoding("UTF-8").gsub!(pattern, replace)
-      else
-        @document_content.force_encoding("UTF-8").sub!(pattern, replace)
+      @document_contents.each do |path, document|
+        if multiple_occurrences
+          document.force_encoding("UTF-8").gsub!(pattern, replace)
+        else
+          document.force_encoding("UTF-8").sub!(pattern, replace)
+        end
       end
     end
 
     def matches(pattern)
-      @document_content.scan(pattern).map{|match| match.first}
+      @document_contents.values.join.scan(pattern).map{|match| match.first}
     end
 
     def unique_matches(pattern)
@@ -39,10 +42,18 @@ def commit(new_path=nil)
     end
 
     private
-    DOCUMENT_FILE_PATH = 'word/document.xml'
 
-    def read_docx_file
-      @document_content = @zip_file.read(DOCUMENT_FILE_PATH)
+    def find_query_file_paths
+      @zip_file.entries.map(&:name).select do |entry|
+        !(/^word\/(document|footer[0-9]+|header[0-9]+).xml$/ =~ entry).nil?
+      end
+    end
+
+    def read_docx_files
+      @document_contents = {}
+      @document_file_paths.each do |path|
+        @document_contents[path] = @zip_file.read(path)
+      end
     end
 
     def write_back_to_file(new_path=nil)
@@ -51,16 +62,19 @@ def write_back_to_file(new_path=nil)
       else
         temp_file = Tempfile.new('docxedit-', @temp_dir)
       end
+
       Zip::OutputStream.open(temp_file.path) do |zos|
         @zip_file.entries.each do |e|
-          unless e.name == DOCUMENT_FILE_PATH
+          unless @document_file_paths.include?(e.name)
             zos.put_next_entry(e.name)
             zos.print e.get_input_stream.read
           end
         end
 
-        zos.put_next_entry(DOCUMENT_FILE_PATH)
-        zos.print @document_content
+        @document_contents.each do |path, document|
+          zos.put_next_entry(path)
+          zos.print document
+        end
       end
 
       if new_path.nil?