diff --git a/basis/alien/c-types/c-types.factor b/basis/alien/c-types/c-types.factor
index 4ff599e0d1..e2f15f5de8 100644
--- a/basis/alien/c-types/c-types.factor
+++ b/basis/alien/c-types/c-types.factor
@@ -554,9 +554,6 @@ M: ulonglong-2-rep rep-component-type drop ulonglong ;
 M: float-4-rep rep-component-type drop float ;
 M: double-2-rep rep-component-type drop double ;
 
-: rep-length ( rep -- n )
-    16 swap rep-component-type heap-size /i ; foldable
-
 : (unsigned-interval) ( bytes -- from to ) [ 0 ] dip 8 * 2^ 1 - ; foldable
 : unsigned-interval ( c-type -- from to ) heap-size (unsigned-interval) ; foldable
 : (signed-interval) ( bytes -- from to ) 8 * 1 - 2^ [ neg ] [ 1 - ] bi ; foldable
diff --git a/basis/cpu/architecture/architecture.factor b/basis/cpu/architecture/architecture.factor
index 734241a5d3..4d99b5a0ed 100644
--- a/basis/cpu/architecture/architecture.factor
+++ b/basis/cpu/architecture/architecture.factor
@@ -169,6 +169,19 @@ M: uint-scalar-rep rep-size drop 4 ;
 M: longlong-scalar-rep rep-size drop 8 ;
 M: ulonglong-scalar-rep rep-size drop 8 ;
 
+GENERIC: rep-length ( rep -- n ) foldable
+
+M: char-16-rep rep-length drop 16 ;
+M: uchar-16-rep rep-length drop 16 ;
+M: short-8-rep rep-length drop 8 ;
+M: ushort-8-rep rep-length drop 8 ;
+M: int-4-rep rep-length drop 4 ;
+M: uint-4-rep rep-length drop 4 ;
+M: longlong-2-rep rep-length drop 2 ;
+M: ulonglong-2-rep rep-length drop 2 ;
+M: float-4-rep rep-length drop 4 ;
+M: double-2-rep rep-length drop 2 ;
+
 GENERIC: rep-component-type ( rep -- n )
 
 ! Methods defined in alien.c-types