diff --git a/src/faebryk/core/parameter.py b/src/faebryk/core/parameter.py
index e1b51300..606ca950 100644
--- a/src/faebryk/core/parameter.py
+++ b/src/faebryk/core/parameter.py
@@ -13,11 +13,21 @@
 from faebryk.core.trait import Trait
 from faebryk.libs.sets import P_Set, Range, Ranges
 from faebryk.libs.units import HasUnit, Quantity, Unit, dimensionless
-from faebryk.libs.util import abstract, cast_assert, find
+from faebryk.libs.util import KeyErrorNotFound, abstract, cast_assert, find
 
 logger = logging.getLogger(__name__)
 
 
+class ParameterOperableException(Exception):
+    def __init__(self, parameter: "ParameterOperatable", msg: str):
+        self.parameter = parameter
+        super().__init__(msg)
+
+
+class ParameterOperableHasNoLiteral(ParameterOperableException):
+    pass
+
+
 # When we make this generic, two types, type T of elements, and type S of known subsets
 # boolean: T == S == bool
 # enum: T == S == Enum
@@ -374,7 +384,12 @@ def get_operators[T: "Expression"](self, types: type[T] | None = None) -> list[T
 
     def get_literal(self) -> Literal:
         iss = self.get_operators(Is)
-        literal_is = find(o for i in iss for o in i.get_literal_operands())
+        try:
+            literal_is = find(o for i in iss for o in i.get_literal_operands())
+        except KeyErrorNotFound:
+            raise ParameterOperableHasNoLiteral(
+                self, f"Parameter {self} has no literal"
+            )
         return literal_is
 
 
diff --git a/src/faebryk/library/has_simple_value_representation_based_on_params_chain.py b/src/faebryk/library/has_simple_value_representation_based_on_params_chain.py
index 67ec9de3..3c84cd5f 100644
--- a/src/faebryk/library/has_simple_value_representation_based_on_params_chain.py
+++ b/src/faebryk/library/has_simple_value_representation_based_on_params_chain.py
@@ -4,10 +4,16 @@
 from dataclasses import dataclass
 
 import faebryk.library._F as F
-from faebryk.core.parameter import Boolean, EnumDomain, Numbers, Parameter
+from faebryk.core.parameter import (
+    Boolean,
+    EnumDomain,
+    Numbers,
+    Parameter,
+    ParameterOperableHasNoLiteral,
+)
 from faebryk.libs.sets import P_Set, Range
 from faebryk.libs.units import Quantity, Unit, to_si_str
-from faebryk.libs.util import KeyErrorNotFound, join_if_non_empty
+from faebryk.libs.util import join_if_non_empty
 
 
 class has_simple_value_representation_based_on_params_chain(
@@ -32,7 +38,7 @@ class Spec:
         def _get_value(self) -> str:
             try:
                 value = self.param.get_literal()
-            except KeyErrorNotFound:
+            except ParameterOperableHasNoLiteral:
                 if self.default is not None:
                     return self.default
                 raise
diff --git a/src/faebryk/libs/picker/jlcpcb/picker_lib.py b/src/faebryk/libs/picker/jlcpcb/picker_lib.py
index 105ac7f4..e05c55d5 100644
--- a/src/faebryk/libs/picker/jlcpcb/picker_lib.py
+++ b/src/faebryk/libs/picker/jlcpcb/picker_lib.py
@@ -4,7 +4,7 @@
 
 import faebryk.library._F as F
 from faebryk.core.module import Module
-from faebryk.core.parameter import Parameter
+from faebryk.core.parameter import EnumDomain, Parameter, ParameterOperableHasNoLiteral
 from faebryk.core.solver import Solver
 from faebryk.libs.e_series import E_SERIES_VALUES
 from faebryk.libs.library import L
@@ -17,7 +17,8 @@
     DescriptiveProperties,
     PickError,
 )
-from faebryk.libs.util import KeyErrorAmbiguous, KeyErrorNotFound, cast_assert
+from faebryk.libs.sets import P_Set
+from faebryk.libs.util import KeyErrorAmbiguous, KeyErrorNotFound
 
 logger = logging.getLogger(__name__)
 
@@ -50,24 +51,22 @@ def f(x: str) -> L.PlainSet[T]:
 
 
 def enum_to_str(x: Parameter, force: bool = True) -> set[str]:
-    # FIXME
-    raise NotImplementedError()
-    val = x.get_most_narrow()
-    if isinstance(val, F.Constant):
-        val = F.Set([val])
-
-    if not isinstance(val, F.Set) or not all(
-        isinstance(inner, F.Constant) for inner in val.params
-    ):
+    assert isinstance(x.domain, EnumDomain)
+    try:
+        val = x.get_literal()
+    except ParameterOperableHasNoLiteral:
         if force:
-            raise ValueError(f"Expected a constant or set of constants, got {val}")
-        else:
-            return set()
+            raise
+        return set()
+
+    if isinstance(val, x.domain.enum_t):
+        return {val.value}
+
+    if isinstance(val, P_Set):
+        # TODO handle sets
+        raise NotImplementedError()
 
-    return {
-        cast_assert(Enum, cast_assert(F.Constant, inner).value).name
-        for inner in val.params
-    }
+    raise ValueError(f"Expected an enum, got {val}")
 
 
 _MAPPINGS_BY_TYPE: dict[type[Module], list[MappingParameterDB]] = {
@@ -501,8 +500,7 @@ def find_led(cmp: Module, solver: Solver):
         .filter_by_stock(qty)
         .filter_by_traits(cmp)
         .filter_by_specified_parameters(mapping)
-        # TODO
-        # .filter_by_attribute_mention(list(enum_to_str(cmp.color, force=False)))
+        .filter_by_attribute_mention(list(enum_to_str(cmp.color, force=False)))
         .sort_by_price(qty)
         .filter_by_module_params_and_attach(cmp, mapping, solver, qty)
     )