diff --git a/src/Data/Syntax/Expression.hs b/src/Data/Syntax/Expression.hs
index 887c9eedb..65aad0f62 100644
--- a/src/Data/Syntax/Expression.hs
+++ b/src/Data/Syntax/Expression.hs
@@ -1,12 +1,12 @@
 {-# LANGUAGE DeriveAnyClass, MultiParamTypeClasses, ScopedTypeVariables, UndecidableInstances, DuplicateRecordFields #-}
 module Data.Syntax.Expression where
 
-import Data.Abstract.Evaluatable
+import Data.Abstract.Evaluatable hiding (Member)
 import Data.Abstract.Number (liftIntegralFrac, liftReal, liftedExponent, liftedFloorDiv)
 import Data.Fixed
 import Data.JSON.Fields
 import Diffing.Algorithm
-import Prologue hiding (index)
+import Prologue hiding (index, Member)
 import Proto3.Suite.Class
 
 -- | Typical prefix function application, like `f(x)` in many languages, or `f x` in Haskell.
@@ -322,9 +322,7 @@ instance Evaluatable MemberAccess where
     pure $! LvalMember ptr propName
 
 -- | Subscript (e.g a[1])
-data Subscript a
-  = Subscript !a ![a]
-  | Member !a !a
+data Subscript a = Subscript { lhs :: a, rhs :: [a] }
   deriving (Declarations1, Diffable, Eq, Foldable, FreeVariables1, Functor, Generic1, Hashable1, Mergeable, Ord, Show, ToJSONFields1, Traversable, Named1, Message1)
 
 instance Eq1 Subscript where liftEq = genericLiftEq
@@ -336,8 +334,15 @@ instance Show1 Subscript where liftShowsPrec = genericLiftShowsPrec
 instance Evaluatable Subscript where
   eval (Subscript l [r]) = Rval <$> join (index <$> subtermValue l <*> subtermValue r)
   eval (Subscript _ _)   = rvalBox =<< throwResumable (Unspecialized "Eval unspecialized for subscript with slices")
-  eval (Member _ _)      = rvalBox =<< throwResumable (Unspecialized "Eval unspecialized for member access")
 
+data Member a = Member { lhs :: a, rhs :: a }
+  deriving (Declarations1, Diffable, Eq, Foldable, FreeVariables1, Functor, Generic1, Hashable1, Mergeable, Ord, Show, ToJSONFields1, Traversable, Named1, Message1)
+
+instance Eq1 Member where liftEq = genericLiftEq
+instance Ord1 Member where liftCompare = genericLiftCompare
+instance Show1 Member where liftShowsPrec = genericLiftShowsPrec
+
+instance Evaluatable Member where
 
 -- | Enumeration (e.g. a[1:10:1] in Python (start at index 1, stop at index 10, step 1 element from start to stop))
 data Enumeration a = Enumeration { enumerationStart :: !a, enumerationEnd :: !a, enumerationStep :: !a }
diff --git a/src/Language/Go/Assignment.hs b/src/Language/Go/Assignment.hs
index 8e092e3fb..f7f18d489 100644
--- a/src/Language/Go/Assignment.hs
+++ b/src/Language/Go/Assignment.hs
@@ -50,6 +50,7 @@ type Syntax =
    , Expression.StrictEqual
    , Expression.Comparison
    , Expression.Subscript
+   , Expression.Member
    , Statement.PostDecrement
    , Statement.PostIncrement
    , Expression.MemberAccess
diff --git a/src/Language/Java/Assignment.hs b/src/Language/Java/Assignment.hs
index 7e3448f05..9a65afb8c 100644
--- a/src/Language/Java/Assignment.hs
+++ b/src/Language/Java/Assignment.hs
@@ -57,6 +57,7 @@ type Syntax =
    , Expression.InstanceOf
    , Expression.MemberAccess
    , Expression.Subscript
+   , Expression.Member
    , Expression.Super
    , Expression.This
    , Java.Syntax.Annotation
diff --git a/src/Language/PHP/Assignment.hs b/src/Language/PHP/Assignment.hs
index ecdc4ef18..91d4d48b3 100644
--- a/src/Language/PHP/Assignment.hs
+++ b/src/Language/PHP/Assignment.hs
@@ -65,6 +65,7 @@ type Syntax = '[
   , Expression.New
   , Expression.SequenceExpression
   , Expression.Subscript
+  , Expression.Member
   , Literal.Array
   , Literal.Float
   , Literal.Integer
diff --git a/src/Language/Python/Assignment.hs b/src/Language/Python/Assignment.hs
index 4f6489642..1ec06f624 100644
--- a/src/Language/Python/Assignment.hs
+++ b/src/Language/Python/Assignment.hs
@@ -71,6 +71,7 @@ type Syntax =
    , Expression.ScopeResolution
    , Expression.MemberAccess
    , Expression.Subscript
+   , Expression.Member
    , Literal.Array
    , Literal.Boolean
    , Literal.Float
diff --git a/src/Language/Ruby/Assignment.hs b/src/Language/Ruby/Assignment.hs
index 9dd98b417..2516a86e6 100644
--- a/src/Language/Ruby/Assignment.hs
+++ b/src/Language/Ruby/Assignment.hs
@@ -69,6 +69,7 @@ type Syntax = '[
   , Expression.MemberAccess
   , Expression.ScopeResolution
   , Expression.Subscript
+  , Expression.Member
   , Literal.Array
   , Literal.Complex
   , Literal.Float
diff --git a/src/Language/TypeScript/Assignment.hs b/src/Language/TypeScript/Assignment.hs
index a7e09eb4d..7bd6ead80 100644
--- a/src/Language/TypeScript/Assignment.hs
+++ b/src/Language/TypeScript/Assignment.hs
@@ -74,6 +74,7 @@ type Syntax = '[
   , Expression.ScopeResolution
   , Expression.SequenceExpression
   , Expression.Subscript
+  , Expression.Member
   , Expression.Delete
   , Expression.Void
   , Expression.Typeof