diff --git a/postpic/_const.py b/postpic/_const.py
index 7a4a009b..5d367003 100644
--- a/postpic/_const.py
+++ b/postpic/_const.py
@@ -28,7 +28,9 @@
                        'PY': 4, 'Py': 4, 'py': 4, 4: 4,
                        'PZ': 5, 'Pz': 5, 'pz': 5, 9: 9,
                        'weight': 9, 'w': 9, 10: 10,
-                       'id': 10, 'ID': 10})
+                       'id': 10, 'ID': 10,
+                       'mass': 11, 'm': 11, 'Mass': 11,
+                       'charge': 12, 'c': 12, 'Charge': 12, 'q': 12})
 
 # Some static functions
 
diff --git a/postpic/analyzer/particles.py b/postpic/analyzer/particles.py
index 4c36a1bd..1fcc7621 100644
--- a/postpic/analyzer/particles.py
+++ b/postpic/analyzer/particles.py
@@ -37,9 +37,12 @@ class _SingleSpeciesAnalyzer(object):
     def __init__(self, dumpreader, species):
         self.species = species
         self._dumpreader = dumpreader
-        self._idfy = identifyspecies(species)
-        self._mass = self._idfy['mass']  # SI
-        self._charge = self._idfy['charge']  # SI
+        self._mass = dumpreader.getSpecies(species, 'mass')
+        self._charge = dumpreader.getSpecies(species, 'charge')
+        if self._mass is None or self._charge is None:
+            self._idfy = identifyspecies(species)
+            self._mass = self._idfy['mass']  # SI
+            self._charge = self._idfy['charge']  # SI
         self.compresslog = []
         self._compressboollist = None
         self._cache = {}