diff --git a/.gitignore b/.gitignore
index 23b40b5..ecf23aa 100644
--- a/.gitignore
+++ b/.gitignore
@@ -4,3 +4,4 @@ lib/
 npm-debug.log
 .node-version
 .DS_Store
+.idea
\ No newline at end of file
diff --git a/README.md b/README.md
index a5671f4..621a31c 100644
--- a/README.md
+++ b/README.md
@@ -69,6 +69,14 @@ Buffer contents of the uncompressed paths.  The `callback` gets two arguments
 `callback` - The function to call after reading completes with an error or
 the Buffer contents.
 
+### archive.configureExtensions(additionalExtensions)
+
+Adds custom file extensions to zip, tar, and/or gzip handling to support archives with atypical extensions.
+
+`additionalExtensions` - Object literal with string arrays for zip, tar, and gzip
+
+Example: `archive.configureExtensions(zip: ['.docx'])`
+
 ### ArchiveEntry
 
 Class representing a path entry inside an archive file.
diff --git a/spec/fixtures/one-file.customZip b/spec/fixtures/one-file.customZip
new file mode 100644
index 0000000..c59cd1d
Binary files /dev/null and b/spec/fixtures/one-file.customZip differ
diff --git a/spec/fixtures/word.docx b/spec/fixtures/word.docx
new file mode 100644
index 0000000..5d59308
Binary files /dev/null and b/spec/fixtures/word.docx differ
diff --git a/spec/zip-spec.coffee b/spec/zip-spec.coffee
index 1b78de5..5514996 100644
--- a/spec/zip-spec.coffee
+++ b/spec/zip-spec.coffee
@@ -71,6 +71,20 @@ describe "zip files", ->
         waitsFor -> pathError?
         runs -> expect(pathError.message.length).toBeGreaterThan 0
 
+    describe "listing when custom extensions are added", ->
+      it "lists files and folders in the docx archive", ->
+        zipPaths = null
+        callback = (error, paths) -> zipPaths = paths
+        archive.configureExtensions(zip: ['.docx'])
+        archive.list(path.join(fixturesRoot, 'word.docx'), forceZip: true, callback)
+        waitsFor -> zipPaths?
+        runs ->
+          expect(zipPaths.length).toBe 13
+          expect(zipPaths[0].path).toBe '[Content_Types].xml'
+          expect(zipPaths[0].isDirectory()).toBe false
+          expect(zipPaths[0].isFile()).toBe true
+          expect(zipPaths[0].isSymbolicLink()).toBe false
+
   describe ".readFile()", ->
     describe "when the path exists in the archive", ->
       it "calls back with the contents of the given path", ->
@@ -116,3 +130,14 @@ describe "zip files", ->
         archive.readFile(archivePath, "folder#{path.sep}", callback)
         waitsFor -> pathError?
         runs -> expect(pathError.message.length).toBeGreaterThan 0
+
+    describe "reading when custom extensions are added", ->
+      it "calls back with the contents of the given path", ->
+        archivePath = path.join(fixturesRoot, 'one-file.customZip')
+        pathContents = null
+        callback = (error, contents) -> pathContents = contents
+        archive.configureExtensions(zip: ['.customZip'])
+        archive.readFile(archivePath, 'file.txt', callback)
+        waitsFor -> pathContents?
+        runs -> expect(pathContents.toString()).toBe 'hello\n'
+
diff --git a/src/ls-archive.coffee b/src/ls-archive.coffee
index 793629f..0d34795 100644
--- a/src/ls-archive.coffee
+++ b/src/ls-archive.coffee
@@ -172,43 +172,54 @@ readEntry = (entry, callback) ->
   entry.on 'data', (data) -> contents.push(data)
   entry.on 'end', -> callback(null, Buffer.concat(contents))
 
-isTarPath = (archivePath) ->
-  path.extname(archivePath) is '.tar'
+isTarPath = (archivePath, extensions) ->
+  path.extname(archivePath) in extensions
 
-isZipPath = (archivePath) ->
+isZipPath = (archivePath, extensions) ->
   extension = path.extname(archivePath)
-  extension in ['.epub', '.jar', '.love', '.war', '.zip', '.egg', '.whl', '.xpi', '.nupkg']
+  extension in extensions
 
-isGzipPath = (archivePath) ->
-  path.extname(archivePath) is '.tgz' or
-    path.extname(path.basename(archivePath, '.gz')) is '.tar'
+isGzipPath = (archivePath, extensions) ->
+  path.extname(archivePath) in extensions.gzip or
+    path.extname(path.basename(archivePath, '.gz')) in extensions.tar
 
 module.exports =
+
+  extensions:
+    zip: ['.epub', '.jar', '.love', '.war', '.zip', '.egg', '.whl', '.xpi', '.nupkg']
+    tar: ['.tar']
+    gzip: ['.tgz']
+
+  configureExtensions: (addlExtensions) ->
+    @extensions.zip.push(addlExtensions.zip...)
+    @extensions.tar.push(addlExtensions.tar...)
+    @extensions.gzip.push(addlExtensions.gzip...)
+
   isPathSupported: (archivePath) ->
     return false unless archivePath
-    isTarPath(archivePath) or isZipPath(archivePath) or isGzipPath(archivePath)
+    isTarPath(archivePath, @extensions.tar) or isZipPath(archivePath, @extensions.zip) or isGzipPath(archivePath, @extensions)
 
   list: (archivePath, options={}, callback) ->
     if typeof options is 'function'
       callback = options
       options = {}
 
-    if isTarPath(archivePath)
+    if isTarPath(archivePath, @extensions.tar)
       listTar(archivePath, options, wrapCallback(callback))
-    else if isGzipPath(archivePath)
+    else if isGzipPath(archivePath, @extensions)
       listGzip(archivePath, options, wrapCallback(callback))
-    else if isZipPath(archivePath)
+    else if isZipPath(archivePath, @extensions.zip)
       listZip(archivePath, options, wrapCallback(callback))
     else
       callback(new Error("'#{path.extname(archivePath)}' files are not supported"))
     undefined
 
   readFile: (archivePath, filePath, callback) ->
-    if isTarPath(archivePath)
+    if isTarPath(archivePath, @extensions.tar)
       readFileFromTar(archivePath, filePath, wrapCallback(callback))
-    else if isGzipPath(archivePath)
+    else if isGzipPath(archivePath, @extensions)
       readFileFromGzip(archivePath, filePath, wrapCallback(callback))
-    else if isZipPath(archivePath)
+    else if isZipPath(archivePath, @extensions.zip)
       readFileFromZip(archivePath, filePath, wrapCallback(callback))
     else
       callback(new Error("'#{path.extname(archivePath)}' files are not supported"))