diff --git a/src/caoscrawler/converters/converters.py b/src/caoscrawler/converters/converters.py
index 3a3c7e292a2967cab68228e820fea6880302be89..bb069e5d44c77dda6aba15020064a7622dc8efd8 100644
--- a/src/caoscrawler/converters/converters.py
+++ b/src/caoscrawler/converters/converters.py
@@ -575,10 +575,17 @@ class Converter(object, metaclass=ABCMeta):
                                        " one element with they key being the name"
                                        " of the function!")
                 tr_func_key = list(tr_func_el.keys())[0]
-                tr_func_params = tr_func_el[tr_func_key]
+
+                # Create a copy of the function parameters:
+                tr_func_params = dict(tr_func_el[tr_func_key])
+
                 if tr_func_key not in transformer_functions:
                     raise RuntimeError("Unknown transformer function: {}".format(tr_func_key))
 
+                # Do variable replacment on function parameters:
+                for key in tr_func_params:
+                    tr_func_params[key] = replace_variables(tr_func_params[key])
+
                 # Retrieve the function from the dictionary:
                 tr_func = transformer_functions[tr_func_key]
                 # Call the function: