diff --git a/core/alien/alien.factor b/core/alien/alien.factor
index 1c8163e2fa..317dac803e 100755
--- a/core/alien/alien.factor
+++ b/core/alien/alien.factor
@@ -1,7 +1,7 @@
 ! Copyright (C) 2004, 2008 Slava Pestov.
 ! See http://factorcode.org/license.txt for BSD license.
 USING: assocs kernel math namespaces sequences system
-kernel.private tuples ;
+kernel.private tuples bit-arrays byte-arrays float-arrays ;
 IN: alien
 
 ! Some predicate classes used by the compiler for optimization
@@ -9,16 +9,11 @@ IN: alien
 PREDICATE: alien simple-alien
     underlying-alien not ;
 
-! These mixins are not intended to be extended by user code.
-! They are not unions, because if they were we'd have a circular
-! dependency between alien and {byte,bit,float}-arrays.
-MIXIN: simple-c-ptr
-INSTANCE: simple-alien simple-c-ptr
-INSTANCE: f simple-c-ptr
+UNION: simple-c-ptr
+simple-alien POSTPONE: f byte-array bit-array float-array ;
 
-MIXIN: c-ptr
-INSTANCE: alien c-ptr
-INSTANCE: f c-ptr
+UNION: c-ptr
+alien POSTPONE: f byte-array bit-array float-array ;
 
 DEFER: pinned-c-ptr?
 
diff --git a/core/bit-arrays/bit-arrays.factor b/core/bit-arrays/bit-arrays.factor
index 4c68d94aad..ee485d399e 100755
--- a/core/bit-arrays/bit-arrays.factor
+++ b/core/bit-arrays/bit-arrays.factor
@@ -1,6 +1,6 @@
 ! Copyright (C) 2007, 2008 Slava Pestov.
 ! See http://factorcode.org/license.txt for BSD license.
-USING: math alien kernel kernel.private sequences
+USING: math alien.accessors kernel kernel.private sequences
 sequences.private ;
 IN: bit-arrays
 
@@ -52,5 +52,3 @@ M: bit-array resize
     resize-bit-array ;
 
 INSTANCE: bit-array sequence
-INSTANCE: bit-array simple-c-ptr
-INSTANCE: bit-array c-ptr
diff --git a/core/bootstrap/image/image.factor b/core/bootstrap/image/image.factor
index f7e0d483f6..c3bf18cffc 100755
--- a/core/bootstrap/image/image.factor
+++ b/core/bootstrap/image/image.factor
@@ -259,6 +259,7 @@ M: wrapper '
     string type-number object tag-number [
         dup length emit-fixnum
         f ' emit
+        f ' emit
         pack-string emit-chars
     ] emit-object ;
 
diff --git a/core/bootstrap/primitives.factor b/core/bootstrap/primitives.factor
index 4c5246e0eb..defbac6720 100755
--- a/core/bootstrap/primitives.factor
+++ b/core/bootstrap/primitives.factor
@@ -40,6 +40,7 @@ call
 ! classes will go
 {
     "alien"
+    "alien.accessors"
     "arrays"
     "bit-arrays"
     "bit-vectors"
@@ -190,6 +191,11 @@ num-types get f <array> builtins set
         "length"
         { "length" "sequences" }
         f
+    } {
+        { "object" "kernel" }
+        "aux"
+        { "string-aux" "strings.private" }
+        { "set-string-aux" "strings.private" }
     }
 } define-builtin
 
@@ -556,32 +562,32 @@ builtins get num-tags get tail f union-class define-class
     { "<byte-array>" "byte-arrays" }
     { "<bit-array>" "bit-arrays" }
     { "<displaced-alien>" "alien" }
-    { "alien-signed-cell" "alien" }
-    { "set-alien-signed-cell" "alien" }
-    { "alien-unsigned-cell" "alien" }
-    { "set-alien-unsigned-cell" "alien" }
-    { "alien-signed-8" "alien" }
-    { "set-alien-signed-8" "alien" }
-    { "alien-unsigned-8" "alien" }
-    { "set-alien-unsigned-8" "alien" }
-    { "alien-signed-4" "alien" }
-    { "set-alien-signed-4" "alien" }
-    { "alien-unsigned-4" "alien" }
-    { "set-alien-unsigned-4" "alien" }
-    { "alien-signed-2" "alien" }
-    { "set-alien-signed-2" "alien" }
-    { "alien-unsigned-2" "alien" }
-    { "set-alien-unsigned-2" "alien" }
-    { "alien-signed-1" "alien" }
-    { "set-alien-signed-1" "alien" }
-    { "alien-unsigned-1" "alien" }
-    { "set-alien-unsigned-1" "alien" }
-    { "alien-float" "alien" }
-    { "set-alien-float" "alien" }
-    { "alien-double" "alien" }
-    { "set-alien-double" "alien" }
-    { "alien-cell" "alien" }
-    { "set-alien-cell" "alien" }
+    { "alien-signed-cell" "alien.accessors" }
+    { "set-alien-signed-cell" "alien.accessors" }
+    { "alien-unsigned-cell" "alien.accessors" }
+    { "set-alien-unsigned-cell" "alien.accessors" }
+    { "alien-signed-8" "alien.accessors" }
+    { "set-alien-signed-8" "alien.accessors" }
+    { "alien-unsigned-8" "alien.accessors" }
+    { "set-alien-unsigned-8" "alien.accessors" }
+    { "alien-signed-4" "alien.accessors" }
+    { "set-alien-signed-4" "alien.accessors" }
+    { "alien-unsigned-4" "alien.accessors" }
+    { "set-alien-unsigned-4" "alien.accessors" }
+    { "alien-signed-2" "alien.accessors" }
+    { "set-alien-signed-2" "alien.accessors" }
+    { "alien-unsigned-2" "alien.accessors" }
+    { "set-alien-unsigned-2" "alien.accessors" }
+    { "alien-signed-1" "alien.accessors" }
+    { "set-alien-signed-1" "alien.accessors" }
+    { "alien-unsigned-1" "alien.accessors" }
+    { "set-alien-unsigned-1" "alien.accessors" }
+    { "alien-float" "alien.accessors" }
+    { "set-alien-float" "alien.accessors" }
+    { "alien-double" "alien.accessors" }
+    { "set-alien-double" "alien.accessors" }
+    { "alien-cell" "alien.accessors" }
+    { "set-alien-cell" "alien.accessors" }
     { "alien>char-string" "alien" }
     { "string>char-alien" "alien" }
     { "alien>u16-string" "alien" }
diff --git a/core/byte-arrays/byte-arrays.factor b/core/byte-arrays/byte-arrays.factor
index 401b151ad0..548c293e7c 100755
--- a/core/byte-arrays/byte-arrays.factor
+++ b/core/byte-arrays/byte-arrays.factor
@@ -1,7 +1,7 @@
 ! Copyright (C) 2007, 2008 Slava Pestov.
 ! See http://factorcode.org/license.txt for BSD license.
-USING: kernel kernel.private alien sequences sequences.private
-math ;
+USING: kernel kernel.private alien.accessors sequences
+sequences.private math ;
 IN: byte-arrays
 
 M: byte-array clone (clone) ;
@@ -19,5 +19,3 @@ M: byte-array resize
     resize-byte-array ;
 
 INSTANCE: byte-array sequence
-INSTANCE: byte-array simple-c-ptr
-INSTANCE: byte-array c-ptr
diff --git a/core/compiler/constants/constants.factor b/core/compiler/constants/constants.factor
index 66fc8d5789..277a64225a 100755
--- a/core/compiler/constants/constants.factor
+++ b/core/compiler/constants/constants.factor
@@ -10,7 +10,7 @@ IN: compiler.constants
 ! These constants must match vm/layouts.h
 : header-offset object tag-number neg ;
 : float-offset 8 float tag-number - ;
-: string-offset 3 bootstrap-cells object tag-number - ;
+: string-offset 4 bootstrap-cells object tag-number - ;
 : profile-count-offset 7 bootstrap-cells object tag-number - ;
 : byte-array-offset 2 bootstrap-cells object tag-number - ;
 : alien-offset 3 bootstrap-cells object tag-number - ;
diff --git a/core/float-arrays/float-arrays.factor b/core/float-arrays/float-arrays.factor
index 445edd550a..33302572de 100755
--- a/core/float-arrays/float-arrays.factor
+++ b/core/float-arrays/float-arrays.factor
@@ -1,6 +1,6 @@
 ! Copyright (C) 2007, 2008 Slava Pestov.
 ! See http://factorcode.org/license.txt for BSD license.
-USING: kernel kernel.private alien sequences
+USING: kernel kernel.private alien.accessors sequences
 sequences.private math math.private ;
 IN: float-arrays
 
@@ -33,8 +33,6 @@ M: float-array resize
     resize-float-array ;
 
 INSTANCE: float-array sequence
-INSTANCE: float-array simple-c-ptr
-INSTANCE: float-array c-ptr
 
 : 1float-array ( x -- array ) 1 swap <float-array> ; flushable
 
diff --git a/core/strings/strings.factor b/core/strings/strings.factor
index 10f38f8298..33efed11e8 100755
--- a/core/strings/strings.factor
+++ b/core/strings/strings.factor
@@ -1,14 +1,20 @@
-! Copyright (C) 2003, 2007 Slava Pestov.
+! Copyright (C) 2003, 2008 Slava Pestov.
 ! See http://factorcode.org/license.txt for BSD license.
 USING: kernel math.private sequences kernel.private
-math sequences.private slots.private ;
+math sequences.private slots.private byte-arrays
+alien.accessors ;
 IN: strings
 
 <PRIVATE
 
-: string-hashcode 2 slot ; inline
+: make-string-aux ( string -- aux )
+    dup string-aux
+    [ ] [ dup length <byte-array> dup rot set-string-aux ] ?if
+    { byte-array } declare ; inline
 
-: set-string-hashcode 2 set-slot ; inline
+: string-hashcode 3 slot ; inline
+
+: set-string-hashcode 3 set-slot ; inline
 
 : reset-string-hashcode f swap set-string-hashcode ; inline
 
diff --git a/vm/debug.c b/vm/debug.c
index 2692bdf59c..5b4320b5e9 100755
--- a/vm/debug.c
+++ b/vm/debug.c
@@ -4,7 +4,7 @@ void print_chars(F_STRING* str)
 {
 	CELL i;
 	for(i = 0; i < string_capacity(str); i++)
-		putchar(cget(SREF(str,i)));
+		putchar(string_nth(str,i));
 }
 
 void print_word(F_WORD* word, CELL nesting)
diff --git a/vm/layouts.h b/vm/layouts.h
index 07e22cfed0..2b8957ee66 100755
--- a/vm/layouts.h
+++ b/vm/layouts.h
@@ -106,6 +106,8 @@ typedef struct {
 	/* tagged num of chars */
 	CELL length;
 	/* tagged */
+	CELL aux;
+	/* tagged */
 	CELL hashcode;
 } F_STRING;
 
diff --git a/vm/types.c b/vm/types.c
index 27a5b55e2b..d5e8d76abb 100755
--- a/vm/types.c
+++ b/vm/types.c
@@ -429,10 +429,11 @@ F_STRING* allot_string_internal(CELL capacity)
 	/* strings are null-terminated in memory, even though they also
 	have a length field. The null termination allows us to add
 	the sizeof(F_STRING) to a Factor string to get a C-style
-	UCS-2 string for C library calls. */
-	cput(SREF(string,capacity),(u16)'\0');
+	char* string for C library calls. */
+	set_string_nth(string,capacity,0);
 	string->length = tag_fixnum(capacity);
 	string->hashcode = F;
+	string->aux = F;
 	return string;
 }
 
@@ -446,7 +447,7 @@ void fill_string(F_STRING *string, CELL start, CELL capacity, CELL fill)
 		CELL i;
 
 		for(i = start; i < capacity; i++)
-			cput(SREF(string,i),fill);
+			set_string_nth(string,i,fill);
 	}
 }
 
@@ -499,7 +500,7 @@ DEFINE_PRIMITIVE(resize_string)
 		CELL i; \
 		for(i = 0; i < length; i++) \
 		{ \
-			cput(SREF(s,i),(utype)*string); \
+			set_string_nth(s,i,(utype)*string); \
 			string++; \
 		} \
 		return s; \