diff --git a/changelog.md b/changelog.md
index 6befbc2..5582543 100644
--- a/changelog.md
+++ b/changelog.md
@@ -2,6 +2,9 @@
 
 ## WIP
 
+- Fix roles for `MVector` and `Vector` to no longer declare their sizes as
+  phantom
+
 ## [1.6.1]
 
 - Fix build against Stackage nightly for GHC 9.4.5
diff --git a/src/Data/Vector/Generic/Mutable/Sized/Internal.hs b/src/Data/Vector/Generic/Mutable/Sized/Internal.hs
index 70a77b7..c3d7976 100644
--- a/src/Data/Vector/Generic/Mutable/Sized/Internal.hs
+++ b/src/Data/Vector/Generic/Mutable/Sized/Internal.hs
@@ -2,6 +2,7 @@
 {-# LANGUAGE DeriveDataTypeable         #-}
 {-# LANGUAGE GeneralizedNewtypeDeriving #-}
 {-# LANGUAGE KindSignatures             #-}
+{-# LANGUAGE RoleAnnotations            #-}
 {-# OPTIONS_HADDOCK not-home            #-}
 
 module Data.Vector.Generic.Mutable.Sized.Internal
@@ -20,3 +21,5 @@ import           Foreign.Storable
 -- which have a different length than that specified in the type parameter!
 newtype MVector v (n :: Nat) s a = MVector (v s a)
   deriving ( Typeable, Data, Storable, NFData )
+
+type role MVector representational nominal nominal nominal
diff --git a/src/Data/Vector/Generic/Sized/Internal.hs b/src/Data/Vector/Generic/Sized/Internal.hs
index 742ea52..5f2114d 100644
--- a/src/Data/Vector/Generic/Sized/Internal.hs
+++ b/src/Data/Vector/Generic/Sized/Internal.hs
@@ -4,6 +4,7 @@
 {-# LANGUAGE FlexibleInstances          #-}
 {-# LANGUAGE GeneralizedNewtypeDeriving #-}
 {-# LANGUAGE KindSignatures             #-}
+{-# LANGUAGE RoleAnnotations            #-}
 {-# OPTIONS_HADDOCK not-home            #-}
 
 module Data.Vector.Generic.Sized.Internal
@@ -52,6 +53,8 @@ newtype Vector v (n :: Nat) a = Vector (v a)
            , Data, Typeable
            )
 
+type role Vector representational nominal nominal
+
 instance (Ix a, Ord (v a), VG.Vector v a) => Ix (Vector v n a) where
 
   -- range is consistent with range :: ((a,..,a), (a,..,a)) -> [(a,..,a)]