diff --git a/qpms/argproc.py b/qpms/argproc.py
index 2295f72..bdbffb2 100644
--- a/qpms/argproc.py
+++ b/qpms/argproc.py
@@ -238,12 +238,14 @@ constant_tmatrix_spec = namedtuple("constant_tmatrix_spec", ("bspec", "matrix"))
 cyl_sph_dimensions = namedtuple("cyl_sph_dimensions", ("radius", "height", "lMax_extend"))
 tmgen_spec = namedtuple("tmgen_spec", ("bgspec", "fgspec", "dims"))
 
-def string2bspec(string):
+def string2bspec_tuple(string):
     """
-    Converts string representation of list to BaseSpec.
+    Converts string representation of list to BaseSpec...
+    And then to tuple, because we want the arguments to be picklable :(
     """
     from .cybspec import BaseSpec
-    return BaseSpec(ast.literal_eval(string))
+    bspec = BaseSpec(ast.literal_eval(string))
+    return tuple(i for i in bspec.ilist)
 
 class ArgParser:
     ''' Common argument parsing engine for QPMS python CLI scripts. '''
@@ -307,10 +309,10 @@ class ArgParser:
                 help='particle radius (cylinder; labeled)')
         # Alternatively, add a constant T-matrix
         mpgrp.add_argument("-w", "--vswf-set", nargs=1, default={},
-                action=make_dict_action(argtype=string2bspec, postaction='store', first_is_key=False),
+                action=make_dict_action(argtype=string2bspec_tuple, postaction='store', first_is_key=False),
                 help='Manual specification of VSWF set codes (format as a python list of integers); see docs on qpms_uvswfi_t for valid codes or simply use --lMax instead. Overrides --lMax.')
         mpgrp.add_argument("+w", "++vswf-set", nargs=2, default={},
-                action=make_dict_action(argtype=string2bspec, postaction='store', first_is_key=True),
+                action=make_dict_action(argtype=string2bspec_tuple, postaction='store', first_is_key=True),
                 metavar=('LABEL', "VSWF_SET"),
                 help='Manual specification of VSWF set codes (format as a python list of integers); see docs on qpms_uvswfi_t for valid codes or simply use ++lMax instead. Overrides ++lMax and --lMax.')
         mpgrp.add_argument("-T", "--constant-tmatrix", nargs=1, default={},