diff --git a/coreapi/help/doc/sphinx/CMakeLists.txt b/coreapi/help/doc/sphinx/CMakeLists.txt
index 052e33ea3..05d7159a2 100644
--- a/coreapi/help/doc/sphinx/CMakeLists.txt
+++ b/coreapi/help/doc/sphinx/CMakeLists.txt
@@ -42,20 +42,7 @@ if (ENABLE_SPHINX_DOC)
 	configure_file(conf.py.in source/conf.py)
 	configure_file(index.rst source/index.rst COPYONLY)
 	configure_file(logo.png source/logo.png COPYONLY)
-	add_custom_command(OUTPUT ${GENERATED_SPHINX_SOURCES}
-		COMMAND ${CMAKE_COMMAND} -E remove -f ${DOCUMENTATION_DIRS}
-		COMMAND ${PYTHON_EXECUTABLE} '${CMAKE_CURRENT_SOURCE_DIR}/gendoc.py' '${LINPHONE_DOXYGEN_XML_DIR}' -o 'source'
-		DEPENDS ${PYTHON_SCRIPTS}
-		${MUSTACHE_TEMPLATES}
-		${LINPHONE_DOXYGEN_XML_DIR}/index.xml
-		linphone-doc
-	)
-	add_custom_command(OUTPUT build/html/index.html
-		COMMAND ${CMAKE_COMMAND} -E remove_directory build
+	add_custom_target(sphinx-doc ALL ${PYTHON_EXECUTABLE} '${CMAKE_CURRENT_SOURCE_DIR}/gendoc.py' '${LINPHONE_DOXYGEN_XML_DIR}' -o 'source'
 		COMMAND ${PYTHON_EXECUTABLE} -msphinx -M html 'source' 'build'
-		DEPENDS ${CMAKE_CURRENT_BINARY_DIR}/source/conf.py
-		${CMAKE_CURRENT_BINARY_DIR}/source/index.rst
-		${GENERATED_SPHINX_SOURCES}
-	)
-	add_custom_target(sphinx-doc ALL DEPENDS build/html/index.html)
+		DEPENDS linphone-doc)
 endif()
diff --git a/coreapi/help/doc/sphinx/gendoc.py b/coreapi/help/doc/sphinx/gendoc.py
index eecedda17..252f68d09 100755
--- a/coreapi/help/doc/sphinx/gendoc.py
+++ b/coreapi/help/doc/sphinx/gendoc.py
@@ -19,6 +19,7 @@
 
 
 import argparse
+import hashlib
 import logging
 import os
 import pystache
@@ -31,6 +32,13 @@ import metaname
 import metadoc
 
 
+def md5sum(file):
+	hasher = hashlib.md5()
+	with open(file, mode='rb') as f:
+		hasher.update(f.read())
+	return hasher.hexdigest()
+
+
 class RstTools:
 	@staticmethod
 	def make_part(text):
@@ -140,6 +148,10 @@ class LangInfo:
 	def displayName(self):
 		return LangInfo._displayNames[self.langCode]
 
+	@property
+	def directory(self):
+		return self.langCode.lower()
+
 	_displayNames = {
 		'C'     : 'C',
 		'Cpp'   : 'C++',
@@ -239,9 +251,15 @@ class SphinxPage(SphinxPart):
 	def write(self, directory):
 		r = pystache.Renderer()
 		filepath = os.path.join(directory, self.filename)
-		with open(filepath, mode='w') as f:
+		tmpFilepath = filepath + '.tmp'
+		with open(tmpFilepath, mode='w') as f:
 			f.write(r.render(self))
-	
+		if os.path.exists(filepath) and md5sum(filepath) == md5sum(tmpFilepath):
+			os.remove(tmpFilepath)
+		else:
+			os.rename(tmpFilepath, filepath)
+		return filepath
+
 	def _get_translated_namespace(self, obj):
 		namespace = obj.find_first_ancestor_by_type(abstractapi.Namespace)
 		return namespace.name.translate(self.lang.nameTranslator, recursive=True)
@@ -263,7 +281,7 @@ class IndexPage(SphinxPage):
 
 	@property
 	def dir(self):
-		return self.lang.langCode.lower()
+		return self.lang.directory
 
 	@property
 	def entries(self):
@@ -390,6 +408,25 @@ class ClassPage(SphinxPage):
 		return table
 
 
+class OldFilesCleaner:
+	def __init__(self, rootDirectory):
+		self._filesToKeep = set()
+		self.root = rootDirectory
+
+	def add_directory(self, directory):
+		self._filesToKeep.add(directory)
+
+	def clean(self):
+		self._clean(self.root)
+
+	def _clean(self, dir_):
+		if os.path.isdir(dir_):
+			for filename in os.listdir(dir_):
+				self._clean(os.path.join(dir_, filename))
+		elif dir_ not in self._filesToKeep:
+			os.remove(dir_)
+
+
 class DocGenerator:
 	def __init__(self, api):
 		self.api = api
@@ -402,20 +439,24 @@ class DocGenerator:
 	
 	def generate(self, outputdir):
 		for lang in self.languages:
+			directory = os.path.join(args.outputdir, lang.directory)
+			cleaner = OldFilesCleaner(directory)
 			indexPage = IndexPage(lang, 'index.rst')
-			subdirectory = lang.langCode.lower()
-			directory = os.path.join(args.outputdir, subdirectory)
 			if not os.path.exists(directory):
 				os.mkdir(directory)
 			for enum in self.api.namespace.enums:
 				page = EnumPage(enum, lang, self.languages)
-				page.write(directory)
+				filepath = page.write(directory)
 				indexPage.add_entry(page.filename)
+				cleaner.add_directory(filepath)
 			for class_ in self.api.namespace.classes:
 				page = ClassPage(class_, lang, self.languages)
-				page.write(directory)
+				filepath = page.write(directory)
 				indexPage.add_entry(page.filename)
-			indexPage.write(directory)
+				cleaner.add_directory(filepath)
+			filepath = indexPage.write(directory)
+			cleaner.add_directory(filepath)
+			cleaner.clean()
 
 
 if __name__ == '__main__':