diff --git a/build_tools/gather_sources.py b/build_tools/gather_sources.py
new file mode 100644
index 0000000..3ff32f4
--- /dev/null
+++ b/build_tools/gather_sources.py
@@ -0,0 +1,91 @@
+import shutil
+import tempfile
+import re
+from git import Repo,Tree,Blob
+
+def apply_license(license, relimit, filename):
+  header = re.sub(r'@FILENAME@', filename, license)
+
+  f = file(filename)
+  lines = f.read()
+  f.close()
+
+  lines = re.sub(relimit, '', lines)
+  lines = header + lines
+
+  with tempfile.NamedTemporaryFile(delete=False) as tmp_sources:
+    tmp_sources.write(lines)
+
+  shutil.move(tmp_sources.name, filename)
+
+
+def apply_python_license(filename):
+  license="""#+
+#   CosmoTool -- A cosmotool box for cosmology -- @FILENAME@
+#   Copyright (C) 2007-2013 Guilhem Lavaux
+#
+#   This program is free software; you can redistribute it and/or modify
+#   it under the terms of the GNU General Public License as published by
+#   the Free Software Foundation; version 2 of the License.
+# 
+#
+#   This program is distributed in the hope that it will be useful,
+#   but WITHOUT ANY WARRANTY; without even the implied warranty of
+#   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+#   GNU General Public License for more details.
+#
+#   You should have received a copy of the GNU General Public License along
+#   with this program; if not, write to the Free Software Foundation, Inc.,
+#   51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+#+
+"""
+   
+  print("Shell/Python file: %s" % filename)
+  relimit=r'^#\+\n(#.*\n)*#\+\n'
+  apply_license(license, relimit, filename)
+
+
+def apply_cpp_license(filename):
+  license="""/*+
+    CosmoTool -- A cosmotool box for cosmology -- @FILENAME@
+    Copyright (C) 2007-2013 Guilhem Lavaux
+
+    This program is free software; you can redistribute it and/or modify
+    it under the terms of the GNU General Public License as published by
+    the Free Software Foundation; version 2 of the License.
+
+    This program is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU General Public License for more details.
+
+    You should have received a copy of the GNU General Public License along
+    with this program; if not, write to the Free Software Foundation, Inc.,
+    51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
++*/
+"""
+  relimit = r'^(?s)/\*\+.*\+\*/'
+  print("C++ file: %s" % filename)
+  apply_license(license, relimit, filename)
+  
+
+def analyze_tree(prefix, t):
+  for ename,entry in t.items():
+    if ename == 'external' or ename == 'zobov':
+      continue
+    if type(entry) == Tree:
+      analyze_tree(prefix + "/" + ename, entry)
+    elif type(entry) == Blob:
+      if re.match(".*\.(sh|py|pyx)$",ename) != None:
+        fname=prefix+"/"+ename
+        apply_python_license(fname)
+      if re.match('.*\.(cpp|hpp|h)$', ename) != None:
+        fname=prefix+"/"+ename
+        apply_cpp_license(fname)
+
+
+if __name__=="__main__":
+  repo = Repo(".")
+  assert repo.bare == False
+  t = repo.tree()
+  analyze_tree(".", t)