diff --git a/sat/plugins/plugin_xep_0300.py b/sat/plugins/plugin_xep_0300.py
index baef30ee..0731b96f 100644
--- a/sat/plugins/plugin_xep_0300.py
+++ b/sat/plugins/plugin_xep_0300.py
@@ -109,16 +109,15 @@ class XEP_0300(object):
 
         /!\\ blocking method, please use calculateHash instead
         @param file_obj(file): a file-like object
-        @param hasher(callable): the method to call to initialise hash object
+        @param hasher(hash object): the method to call to initialise hash object
         @return (str): the hex digest of the hash
         """
-        hash_ = hasher()
         while True:
             buf = file_obj.read(BUFFER_SIZE)
             if not buf:
                 break
-            hash_.update(buf)
-        return hash_.hexdigest()
+            hasher.update(buf)
+        return hasher.hexdigest()
 
     def calculateHash(self, file_obj, hasher):
         return threads.deferToThread(self._calculateHashBlocking, file_obj, hasher)
@@ -134,7 +133,7 @@ class XEP_0300(object):
         def hashCalculated(hash_):
             return self.buildHashElt(hash_, algo)
 
-        hasher = self.ALGOS[algo]
+        hasher = self.getHasher(algo)
         hash_d = self.calculateHash(file_obj, hasher)
         hash_d.addCallback(hashCalculated)
         return hash_d