diff --git a/build/mech_converter.py b/build/mech_converter.py
index 9414c728..76e86ebd 100644
--- a/build/mech_converter.py
+++ b/build/mech_converter.py
@@ -58,8 +58,8 @@ def tokenise_and_process(input_string, variablesDict):
     assert isinstance(variablesDict, dict), 'tokenise_and_process: variablesDict is not of type dict: ' + str(variablesDict)
 
     # Generate start and end points of sections of symbols and nonsymbols
-    symbol_regex = '[()\-+*@/ ]+'
-    nonsymbol_regex = '[^()\-+*@/ ]+'
+    symbol_regex = '[()\-+*@/, ]+'
+    nonsymbol_regex = '[^()\-+*@/, ]+'
     list_of_symbol_starts = [m.start(0) for m in re.finditer(symbol_regex, input_string)]
     list_of_symbol_ends = [m.end(0) for m in re.finditer(symbol_regex, input_string)]
     list_of_nonsymbol_starts = [m.start(0) for m in re.finditer(nonsymbol_regex, input_string)]