diff --git a/phasm/type3/constraints.py b/phasm/type3/constraints.py
index 4b5a24c..acd0810 100644
--- a/phasm/type3/constraints.py
+++ b/phasm/type3/constraints.py
@@ -33,13 +33,13 @@ class RequireTypeSubstitutes:
     typing of the program, so this constraint can be updated.
     """
 
-SubstitutionMap = Dict[placeholders.PlaceholderForType, types.Type3]
+SubstitutionMap = Dict[PlaceholderForType, types.Type3]
 
 NewConstraintList = List['ConstraintBase']
 
 CheckResult = Union[None, SubstitutionMap, Error, NewConstraintList, RequireTypeSubstitutes]
 
-HumanReadableRet = Tuple[str, Dict[str, Union[str, ourlang.Expression, types.Type3, placeholders.PlaceholderForType]]]
+HumanReadableRet = Tuple[str, Dict[str, Union[str, ourlang.Expression, types.Type3, PlaceholderForType]]]
 
 class Context:
     """
@@ -99,9 +99,9 @@ class SameTypeConstraint(ConstraintBase):
     """
     __slots__ = ('type_list', )
 
-    type_list: List[placeholders.Type3OrPlaceholder]
+    type_list: List[PlaceholderForType]
 
-    def __init__(self, *type_list: placeholders.Type3OrPlaceholder, comment: Optional[str] = None) -> None:
+    def __init__(self, *type_list: PlaceholderForType, comment: Optional[str] = None) -> None:
         super().__init__(comment=comment)
 
         assert len(type_list) > 1
@@ -111,18 +111,10 @@ class SameTypeConstraint(ConstraintBase):
         known_types: List[types.Type3] = []
         phft_list = []
         for typ in self.type_list:
-            if isinstance(typ, types.Type3):
-                known_types.append(typ)
-                continue
-
-            if isinstance(typ, placeholders.PlaceholderForType):
-                if typ.resolve_as is not None:
-                    known_types.append(typ.resolve_as)
-                else:
-                    phft_list.append(typ)
-                continue
-
-            raise NotImplementedError(typ)
+            if typ.resolve_as is not None:
+                known_types.append(typ.resolve_as)
+            else:
+                phft_list.append(typ)
 
         if not known_types:
             return RequireTypeSubstitutes()
@@ -158,7 +150,7 @@ class SameTypeConstraint(ConstraintBase):
         return f'SameTypeConstraint({args}, comment={repr(self.comment)})'
 
 class TupleMatchConstraint(ConstraintBase):
-    def __init__(self, exp_type: placeholders.Type3OrPlaceholder, args: Iterable[placeholders.Type3OrPlaceholder], comment: str):
+    def __init__(self, exp_type: PlaceholderForType, args: Iterable[PlaceholderForType], comment: str):
         super().__init__(comment=comment)
 
         self.exp_type = exp_type
@@ -166,7 +158,7 @@ class TupleMatchConstraint(ConstraintBase):
 
     def check(self) -> CheckResult:
         exp_type = self.exp_type
-        if isinstance(exp_type, placeholders.PlaceholderForType):
+        if isinstance(exp_type, PlaceholderForType):
             if exp_type.resolve_as is None:
                 return RequireTypeSubstitutes()
 
@@ -206,13 +198,13 @@ class MustImplementTypeClassConstraint(ConstraintBase):
 
     context: Context
     type_class3: Union[str, typeclasses.Type3Class]
-    types: list[placeholders.Type3OrPlaceholder]
+    types: list[PlaceholderForType]
 
     DATA = {
         'bytes': {'Foldable'},
     }
 
-    def __init__(self, context: Context, type_class3: Union[str, typeclasses.Type3Class], types: list[placeholders.Type3OrPlaceholder], comment: Optional[str] = None) -> None:
+    def __init__(self, context: Context, type_class3: Union[str, typeclasses.Type3Class], types: list[PlaceholderForType], comment: Optional[str] = None) -> None:
         super().__init__(comment=comment)
 
         self.context = context
@@ -222,10 +214,10 @@ class MustImplementTypeClassConstraint(ConstraintBase):
     def check(self) -> CheckResult:
         typ_list = []
         for typ in self.types:
-            if isinstance(typ, placeholders.PlaceholderForType) and typ.resolve_as is not None:
+            if isinstance(typ, PlaceholderForType) and typ.resolve_as is not None:
                 typ = typ.resolve_as
 
-            if isinstance(typ, placeholders.PlaceholderForType):
+            if isinstance(typ, PlaceholderForType):
                 return RequireTypeSubstitutes()
 
             typ_list.append(typ)
@@ -267,12 +259,12 @@ class LiteralFitsConstraint(ConstraintBase):
     """
     __slots__ = ('type3', 'literal', )
 
-    type3: placeholders.Type3OrPlaceholder
+    type3: PlaceholderForType
     literal: Union[ourlang.ConstantPrimitive, ourlang.ConstantBytes, ourlang.ConstantTuple, ourlang.ConstantStruct]
 
     def __init__(
             self,
-            type3: placeholders.Type3OrPlaceholder,
+            type3: PlaceholderForType,
             literal: Union[ourlang.ConstantPrimitive, ourlang.ConstantBytes, ourlang.ConstantTuple, ourlang.ConstantStruct],
             comment: Optional[str] = None,
         ) -> None:
@@ -296,7 +288,7 @@ class LiteralFitsConstraint(ConstraintBase):
             'f64': None,
         }
 
-        if isinstance(self.type3, placeholders.PlaceholderForType):
+        if isinstance(self.type3, PlaceholderForType):
             if self.type3.resolve_as is None:
                 return RequireTypeSubstitutes()
 
@@ -436,17 +428,17 @@ class CanBeSubscriptedConstraint(ConstraintBase):
     """
     __slots__ = ('ret_type3', 'type3', 'index', 'index_phft', )
 
-    ret_type3: placeholders.Type3OrPlaceholder
-    type3: placeholders.Type3OrPlaceholder
+    ret_type3: PlaceholderForType
+    type3: PlaceholderForType
     index: ourlang.Expression
-    index_phft: placeholders.Type3OrPlaceholder
+    index_phft: PlaceholderForType
 
     def __init__(
             self,
-            ret_type3: placeholders.PlaceholderForType,
-            type3: placeholders.PlaceholderForType,
+            ret_type3: PlaceholderForType,
+            type3: PlaceholderForType,
             index: ourlang.Expression,
-            index_phft: placeholders.PlaceholderForType,
+            index_phft: PlaceholderForType,
             comment: Optional[str] = None,
         ) -> None:
         super().__init__(comment=comment)
@@ -458,7 +450,7 @@ class CanBeSubscriptedConstraint(ConstraintBase):
 
     def check(self) -> CheckResult:
         exp_type = self.type3
-        if isinstance(exp_type, placeholders.PlaceholderForType):
+        if isinstance(exp_type, PlaceholderForType):
             if exp_type.resolve_as is None:
                 return RequireTypeSubstitutes()