diff --git a/pySim/esim/saip/param_source.py b/pySim/esim/saip/param_source.py
index 87842619..adda445c 100644
--- a/pySim/esim/saip/param_source.py
+++ b/pySim/esim/saip/param_source.py
@@ -20,6 +20,7 @@
 import random
 import re
 from pySim.utils import all_subclasses_of
+from osmocom.utils import b2h
 
 class ParamSourceExn(Exception):
     pass
@@ -153,7 +154,7 @@ class RandomHexDigitSource(InputExpandingParamSource):
 
     def get_next(self, csv_row:dict=None):
         val = random.randbytes(self.num_digits // 2) # TODO secure random source?
-        return val
+        return b2h(val)
 
     @classmethod
     def from_str(cls, s:str):