diff --git a/openerp/report/render/rml2html/utils.py b/openerp/report/render/rml2html/utils.py
index 9d1d15da14c..b811cc5d47b 100644
--- a/openerp/report/render/rml2html/utils.py
+++ b/openerp/report/render/rml2html/utils.py
@@ -48,7 +48,9 @@ def tuple_int_get(node, attr_name, default=None):
 def bool_get(value):
     return (str(value)=="1") or (value.lower()=='yes')
 
-def attr_get(node, attrs, dict={}):
+def attr_get(node, attrs, dict=None):
+    if dict is None:
+        dict = {}
     res = {}
     for name in attrs:
         if node.get(name):
diff --git a/openerp/report/render/rml2pdf/trml2pdf.py b/openerp/report/render/rml2pdf/trml2pdf.py
index 09690fb75c2..639d62a1aa9 100644
--- a/openerp/report/render/rml2pdf/trml2pdf.py
+++ b/openerp/report/render/rml2pdf/trml2pdf.py
@@ -226,7 +226,9 @@ class _rml_styles(object,):
         return style
 
 class _rml_doc(object):
-    def __init__(self, node, localcontext, images={}, path='.', title=None):
+    def __init__(self, node, localcontext, images=None, path='.', title=None):
+        if images is None:
+            images = {}
         self.localcontext = localcontext
         self.etree = node
         self.filename = self.etree.get('filename')
@@ -311,7 +313,9 @@ class _rml_doc(object):
             self.canvas.save()
 
 class _rml_canvas(object):
-    def __init__(self, canvas, localcontext, doc_tmpl=None, doc=None, images={}, path='.', title=None):
+    def __init__(self, canvas, localcontext, doc_tmpl=None, doc=None, images=None, path='.', title=None):
+        if images is None:
+            images = {}
         self.localcontext = localcontext
         self.canvas = canvas
         self.styles = doc.styles
@@ -564,7 +568,9 @@ class _rml_canvas(object):
                 tags[n.tag](n)
 
 class _rml_draw(object):
-    def __init__(self, localcontext ,node, styles, images={}, path='.', title=None):
+    def __init__(self, localcontext, node, styles, images=None, path='.', title=None):
+        if images is None:
+            images = {}
         self.localcontext = localcontext
         self.node = node
         self.styles = styles
@@ -595,10 +601,12 @@ class _rml_Illustration(platypus.flowables.Flowable):
 
 class _rml_flowable(object):
     def __init__(self, doc, localcontext, images=None, path='.', title=None):
+        if images is None:
+            images = {}
         self.localcontext = localcontext
         self.doc = doc
         self.styles = doc.styles
-        self.images = images or {}
+        self.images = images
         self.path = path
         self.title = title
         self._logger = logging.getLogger('report.rml.flowable')
@@ -890,7 +898,9 @@ class TinyDocTemplate(platypus.BaseDocTemplate):
             self.canv._pageNumber = 0
 
 class _rml_template(object):
-    def __init__(self, localcontext, out, node, doc, images={}, path='.', title=None):
+    def __init__(self, localcontext, out, node, doc, images=None, path='.', title=None):
+        if images is None:
+            images = {}
         if not localcontext:
             localcontext={'internal_header':True}
         self.localcontext = localcontext
@@ -951,12 +961,12 @@ class _rml_template(object):
             fis.append(PageCount())
             self.doc_tmpl.build(fis)
 
-def parseNode(rml, localcontext=None,fout=None, images=None, path='.',title=None):
-    node = etree.XML(rml)
+def parseNode(rml, localcontext=None, fout=None, images=None, path='.', title=None):
     if localcontext is None:
         localcontext = {}
     if images is None:
         images = {}
+    node = etree.XML(rml)
     r = _rml_doc(node, localcontext, images, path, title=title)
     #try to override some font mappings
     try:
@@ -972,7 +982,11 @@ def parseNode(rml, localcontext=None,fout=None, images=None, path='.',title=None
     r.render(fp)
     return fp.getvalue()
 
-def parseString(rml, localcontext = {},fout=None, images={}, path='.',title=None):
+def parseString(rml, localcontext=None, fout=None, images=None, path='.', title=None):
+    if localcontext is None:
+        localcontext = {}
+    if images is None:
+        images = {}
     node = etree.XML(rml)
     r = _rml_doc(node, localcontext, images, path, title=title)
 
diff --git a/openerp/report/render/rml2pdf/utils.py b/openerp/report/render/rml2pdf/utils.py
index 656045c5c62..cd6b629d84f 100644
--- a/openerp/report/render/rml2pdf/utils.py
+++ b/openerp/report/render/rml2pdf/utils.py
@@ -179,7 +179,9 @@ def tuple_int_get(node, attr_name, default=None):
 def bool_get(value):
     return (str(value)=="1") or (value.lower()=='yes')
 
-def attr_get(node, attrs, dict={}):
+def attr_get(node, attrs, dict=None):
+    if dict is None:
+        dict = {}
     res = {}
     for name in attrs:
         if node.get(name):
diff --git a/openerp/report/render/rml2txt/rml2txt.py b/openerp/report/render/rml2txt/rml2txt.py
index b6e5b54c357..3e0fcf37bdd 100755
--- a/openerp/report/render/rml2txt/rml2txt.py
+++ b/openerp/report/render/rml2txt/rml2txt.py
@@ -375,7 +375,7 @@ class _rml_draw_style(object):
         return ';'.join(['%s:%s' % (x[0],x[1]) for x in self.style[tag].items()])
 
 class _rml_template(object):
-    def __init__(self, localcontext, out, node, doc, images={}, path='.', title=None):
+    def __init__(self, localcontext, out, node, doc, images=None, path='.', title=None):
         self.localcontext = localcontext
         self.frame_pos = -1
         self.frames = []
@@ -465,7 +465,7 @@ class _rml_template(object):
         return result
 
 class _rml_doc(object):
-    def __init__(self, node, localcontext, images={}, path='.', title=None):
+    def __init__(self, node, localcontext, images=None, path='.', title=None):
         self.localcontext = localcontext
         self.etree = node
         self.filename = self.etree.get('filename')
@@ -495,14 +495,18 @@ class _rml_doc(object):
         self.result += '\n'
         out.write( self.result)
 
-def parseNode(rml, localcontext = {},fout=None, images={}, path='.',title=None):
+def parseNode(rml, localcontext = {},fout=None, images=None, path='.',title=None):
+    if images is None:
+        images = {}
     node = etree.XML(rml)
     r = _rml_doc(node, localcontext, images, path, title=title)
     fp = StringIO.StringIO()
     r.render(fp)
     return fp.getvalue()
 
-def parseString(rml, localcontext = {},fout=None, images={}, path='.',title=None):
+def parseString(rml, localcontext = {},fout=None, images=None, path='.',title=None):
+    if images is None:
+        images = {}
     node = etree.XML(rml)
     r = _rml_doc(node, localcontext, images, path, title=title)
     if fout:
diff --git a/openerp/report/render/rml2txt/utils.py b/openerp/report/render/rml2txt/utils.py
index d967b64c53d..122411afb2d 100644
--- a/openerp/report/render/rml2txt/utils.py
+++ b/openerp/report/render/rml2txt/utils.py
@@ -112,7 +112,9 @@ def tuple_int_get(node, attr_name, default=None):
 def bool_get(value):
     return (str(value)=="1") or (value.lower()=='yes')
 
-def attr_get(node, attrs, dict={}):
+def attr_get(node, attrs, dict=None):
+    if dict is None:
+        dict = {}
     res = {}
     for name in attrs:
         if node.get(name):