diff --git a/libguile/vm-engine.c b/libguile/vm-engine.c
index 53c719d05..1be9a4f30 100644
--- a/libguile/vm-engine.c
+++ b/libguile/vm-engine.c
@@ -2932,6 +2932,31 @@ RTL_VM_NAME (SCM vm, SCM program, SCM *argv, size_t nargs_)
       NEXT (1);
     }
 
+  /* constant-vector-set! dst:8 idx:8 src:8
+   *
+   * Store SRC into the vector DST at index IDX.  Here IDX is an
+   * immediate value.
+   */
+  VM_DEFINE_OP (93, constant_vector_set, "constant-vector-set!", OP1 (U8_U8_U8_U8))
+    {
+      scm_t_uint8 dst, idx, src;
+      SCM vect, val;
+
+      SCM_UNPACK_RTL_8_8_8 (op, dst, idx, src);
+      vect = LOCAL_REF (dst);
+      val = LOCAL_REF (src);
+
+      if (SCM_LIKELY (SCM_I_IS_NONWEAK_VECTOR (vect)
+                      && idx < SCM_I_VECTOR_LENGTH (vect)))
+        SCM_I_VECTOR_WELTS (vect)[idx] = val;
+      else
+        {
+          SYNC_IP ();
+          scm_vector_set_x (vect, scm_from_uint8 (idx), val);
+        }
+      NEXT (1);
+    }
+
 
   
 
@@ -2943,7 +2968,7 @@ RTL_VM_NAME (SCM vm, SCM program, SCM *argv, size_t nargs_)
    *
    * Store the vtable of SRC into DST.
    */
-  VM_DEFINE_OP (93, struct_vtable, "struct-vtable", OP1 (U8_U12_U12) | OP_DST)
+  VM_DEFINE_OP (94, struct_vtable, "struct-vtable", OP1 (U8_U12_U12) | OP_DST)
     {
       ARGS1 (obj);
       VM_VALIDATE_STRUCT (obj, "struct_vtable");
@@ -2956,7 +2981,7 @@ RTL_VM_NAME (SCM vm, SCM program, SCM *argv, size_t nargs_)
    * will be constructed with space for NFIELDS fields, which should
    * correspond to the field count of the VTABLE.
    */
-  VM_DEFINE_OP (94, allocate_struct, "allocate-struct", OP1 (U8_U8_U8_U8) | OP_DST)
+  VM_DEFINE_OP (95, allocate_struct, "allocate-struct", OP1 (U8_U8_U8_U8) | OP_DST)
     {
       scm_t_uint8 dst, vtable, nfields;
       SCM ret;
@@ -2975,7 +3000,7 @@ RTL_VM_NAME (SCM vm, SCM program, SCM *argv, size_t nargs_)
    * Fetch the item at slot IDX in the struct in SRC, and store it
    * in DST.
    */
-  VM_DEFINE_OP (95, struct_ref, "struct-ref", OP1 (U8_U8_U8_U8) | OP_DST)
+  VM_DEFINE_OP (96, struct_ref, "struct-ref", OP1 (U8_U8_U8_U8) | OP_DST)
     {
       ARGS2 (obj, pos);
 
@@ -3009,7 +3034,7 @@ RTL_VM_NAME (SCM vm, SCM program, SCM *argv, size_t nargs_)
    *
    * Store SRC into the struct DST at slot IDX.
    */
-  VM_DEFINE_OP (96, struct_set, "struct-set!", OP1 (U8_U8_U8_U8))
+  VM_DEFINE_OP (97, struct_set, "struct-set!", OP1 (U8_U8_U8_U8))
     {
       scm_t_uint8 dst, idx, src;
       SCM obj, pos, val;
@@ -3050,7 +3075,7 @@ RTL_VM_NAME (SCM vm, SCM program, SCM *argv, size_t nargs_)
    *
    * Store the vtable of SRC into DST.
    */
-  VM_DEFINE_OP (97, class_of, "class-of", OP1 (U8_U12_U12) | OP_DST)
+  VM_DEFINE_OP (98, class_of, "class-of", OP1 (U8_U12_U12) | OP_DST)
     {
       ARGS1 (obj);
       if (SCM_INSTANCEP (obj))
@@ -3065,7 +3090,7 @@ RTL_VM_NAME (SCM vm, SCM program, SCM *argv, size_t nargs_)
    * DST.  Unlike struct-ref, IDX is an 8-bit immediate value, not an
    * index into the stack.
    */
-  VM_DEFINE_OP (98, slot_ref, "slot-ref", OP1 (U8_U8_U8_U8) | OP_DST)
+  VM_DEFINE_OP (99, slot_ref, "slot-ref", OP1 (U8_U8_U8_U8) | OP_DST)
     {
       scm_t_uint8 dst, src, idx;
       SCM_UNPACK_RTL_8_8_8 (op, dst, src, idx);
@@ -3079,7 +3104,7 @@ RTL_VM_NAME (SCM vm, SCM program, SCM *argv, size_t nargs_)
    * Store SRC into slot IDX of the struct in DST.  Unlike struct-set!,
    * IDX is an 8-bit immediate value, not an index into the stack.
    */
-  VM_DEFINE_OP (99, slot_set, "slot-set!", OP1 (U8_U8_U8_U8))
+  VM_DEFINE_OP (100, slot_set, "slot-set!", OP1 (U8_U8_U8_U8))
     {
       scm_t_uint8 dst, idx, src;
       SCM_UNPACK_RTL_8_8_8 (op, dst, idx, src);
@@ -3100,7 +3125,7 @@ RTL_VM_NAME (SCM vm, SCM program, SCM *argv, size_t nargs_)
    * from the instruction pointer, and store into DST.  LEN is a byte
    * length.  OFFSET is signed.
    */
-  VM_DEFINE_OP (100, load_typed_array, "load-typed-array", OP3 (U8_U8_U8_U8, N32, U32) | OP_DST)
+  VM_DEFINE_OP (101, load_typed_array, "load-typed-array", OP3 (U8_U8_U8_U8, N32, U32) | OP_DST)
     {
       scm_t_uint8 dst, type, shape;
       scm_t_int32 offset;
@@ -3120,7 +3145,7 @@ RTL_VM_NAME (SCM vm, SCM program, SCM *argv, size_t nargs_)
    *
    * Make a new array with TYPE, FILL, and BOUNDS, storing it in DST.
    */
-  VM_DEFINE_OP (101, make_array, "make-array", OP2 (U8_U12_U12, X8_U12_U12) | OP_DST)
+  VM_DEFINE_OP (102, make_array, "make-array", OP2 (U8_U12_U12, X8_U12_U12) | OP_DST)
     {
       scm_t_uint16 dst, type, fill, bounds;
       SCM_UNPACK_RTL_12_12 (op, dst, type);
@@ -3218,42 +3243,42 @@ RTL_VM_NAME (SCM vm, SCM program, SCM *argv, size_t nargs_)
       RETURN (scm_bytevector_ ## fn_stem ## _native_ref (bv, idx));	\
   } while (0)
 
-  VM_DEFINE_OP (102, bv_u8_ref, "bv-u8-ref", OP1 (U8_U8_U8_U8) | OP_DST)
+  VM_DEFINE_OP (103, bv_u8_ref, "bv-u8-ref", OP1 (U8_U8_U8_U8) | OP_DST)
     BV_FIXABLE_INT_REF (u8, u8, uint8, 1);
 
-  VM_DEFINE_OP (103, bv_s8_ref, "bv-s8-ref", OP1 (U8_U8_U8_U8) | OP_DST)
+  VM_DEFINE_OP (104, bv_s8_ref, "bv-s8-ref", OP1 (U8_U8_U8_U8) | OP_DST)
     BV_FIXABLE_INT_REF (s8, s8, int8, 1);
 
-  VM_DEFINE_OP (104, bv_u16_ref, "bv-u16-ref", OP1 (U8_U8_U8_U8) | OP_DST)
+  VM_DEFINE_OP (105, bv_u16_ref, "bv-u16-ref", OP1 (U8_U8_U8_U8) | OP_DST)
     BV_FIXABLE_INT_REF (u16, u16_native, uint16, 2);
 
-  VM_DEFINE_OP (105, bv_s16_ref, "bv-s16-ref", OP1 (U8_U8_U8_U8) | OP_DST)
+  VM_DEFINE_OP (106, bv_s16_ref, "bv-s16-ref", OP1 (U8_U8_U8_U8) | OP_DST)
     BV_FIXABLE_INT_REF (s16, s16_native, int16, 2);
 
-  VM_DEFINE_OP (106, bv_u32_ref, "bv-u32-ref", OP1 (U8_U8_U8_U8) | OP_DST)
+  VM_DEFINE_OP (107, bv_u32_ref, "bv-u32-ref", OP1 (U8_U8_U8_U8) | OP_DST)
 #if SIZEOF_VOID_P > 4
     BV_FIXABLE_INT_REF (u32, u32_native, uint32, 4);
 #else
     BV_INT_REF (u32, uint32, 4);
 #endif
 
-  VM_DEFINE_OP (107, bv_s32_ref, "bv-s32-ref", OP1 (U8_U8_U8_U8) | OP_DST)
+  VM_DEFINE_OP (108, bv_s32_ref, "bv-s32-ref", OP1 (U8_U8_U8_U8) | OP_DST)
 #if SIZEOF_VOID_P > 4
     BV_FIXABLE_INT_REF (s32, s32_native, int32, 4);
 #else
     BV_INT_REF (s32, int32, 4);
 #endif
 
-  VM_DEFINE_OP (108, bv_u64_ref, "bv-u64-ref", OP1 (U8_U8_U8_U8) | OP_DST)
+  VM_DEFINE_OP (109, bv_u64_ref, "bv-u64-ref", OP1 (U8_U8_U8_U8) | OP_DST)
     BV_INT_REF (u64, uint64, 8);
 
-  VM_DEFINE_OP (109, bv_s64_ref, "bv-s64-ref", OP1 (U8_U8_U8_U8) | OP_DST)
+  VM_DEFINE_OP (110, bv_s64_ref, "bv-s64-ref", OP1 (U8_U8_U8_U8) | OP_DST)
     BV_INT_REF (s64, int64, 8);
 
-  VM_DEFINE_OP (110, bv_f32_ref, "bv-f32-ref", OP1 (U8_U8_U8_U8) | OP_DST)
+  VM_DEFINE_OP (111, bv_f32_ref, "bv-f32-ref", OP1 (U8_U8_U8_U8) | OP_DST)
     BV_FLOAT_REF (f32, ieee_single, float, 4);
 
-  VM_DEFINE_OP (111, bv_f64_ref, "bv-f64-ref", OP1 (U8_U8_U8_U8) | OP_DST)
+  VM_DEFINE_OP (112, bv_f64_ref, "bv-f64-ref", OP1 (U8_U8_U8_U8) | OP_DST)
     BV_FLOAT_REF (f64, ieee_double, double, 8);
 
   /* bv-u8-set! dst:8 idx:8 src:8
@@ -3357,42 +3382,42 @@ RTL_VM_NAME (SCM vm, SCM program, SCM *argv, size_t nargs_)
     NEXT (1);                                                           \
   } while (0)
 
-  VM_DEFINE_OP (112, bv_u8_set, "bv-u8-set!", OP1 (U8_U8_U8_U8))
+  VM_DEFINE_OP (113, bv_u8_set, "bv-u8-set!", OP1 (U8_U8_U8_U8))
     BV_FIXABLE_INT_SET (u8, u8, uint8, 0, SCM_T_UINT8_MAX, 1);
 
-  VM_DEFINE_OP (113, bv_s8_set, "bv-s8-set!", OP1 (U8_U8_U8_U8))
+  VM_DEFINE_OP (114, bv_s8_set, "bv-s8-set!", OP1 (U8_U8_U8_U8))
     BV_FIXABLE_INT_SET (s8, s8, int8, SCM_T_INT8_MIN, SCM_T_INT8_MAX, 1);
 
-  VM_DEFINE_OP (114, bv_u16_set, "bv-u16-set!", OP1 (U8_U8_U8_U8))
+  VM_DEFINE_OP (115, bv_u16_set, "bv-u16-set!", OP1 (U8_U8_U8_U8))
     BV_FIXABLE_INT_SET (u16, u16_native, uint16, 0, SCM_T_UINT16_MAX, 2);
 
-  VM_DEFINE_OP (115, bv_s16_set, "bv-s16-set!", OP1 (U8_U8_U8_U8))
+  VM_DEFINE_OP (116, bv_s16_set, "bv-s16-set!", OP1 (U8_U8_U8_U8))
     BV_FIXABLE_INT_SET (s16, s16_native, int16, SCM_T_INT16_MIN, SCM_T_INT16_MAX, 2);
 
-  VM_DEFINE_OP (116, bv_u32_set, "bv-u32-set!", OP1 (U8_U8_U8_U8))
+  VM_DEFINE_OP (117, bv_u32_set, "bv-u32-set!", OP1 (U8_U8_U8_U8))
 #if SIZEOF_VOID_P > 4
     BV_FIXABLE_INT_SET (u32, u32_native, uint32, 0, SCM_T_UINT32_MAX, 4);
 #else
     BV_INT_SET (u32, uint32, 4);
 #endif
 
-  VM_DEFINE_OP (117, bv_s32_set, "bv-s32-set!", OP1 (U8_U8_U8_U8))
+  VM_DEFINE_OP (118, bv_s32_set, "bv-s32-set!", OP1 (U8_U8_U8_U8))
 #if SIZEOF_VOID_P > 4
     BV_FIXABLE_INT_SET (s32, s32_native, int32, SCM_T_INT32_MIN, SCM_T_INT32_MAX, 4);
 #else
     BV_INT_SET (s32, int32, 4);
 #endif
 
-  VM_DEFINE_OP (118, bv_u64_set, "bv-u64-set!", OP1 (U8_U8_U8_U8))
+  VM_DEFINE_OP (119, bv_u64_set, "bv-u64-set!", OP1 (U8_U8_U8_U8))
     BV_INT_SET (u64, uint64, 8);
 
-  VM_DEFINE_OP (119, bv_s64_set, "bv-s64-set!", OP1 (U8_U8_U8_U8))
+  VM_DEFINE_OP (120, bv_s64_set, "bv-s64-set!", OP1 (U8_U8_U8_U8))
     BV_INT_SET (s64, int64, 8);
 
-  VM_DEFINE_OP (120, bv_f32_set, "bv-f32-set!", OP1 (U8_U8_U8_U8))
+  VM_DEFINE_OP (121, bv_f32_set, "bv-f32-set!", OP1 (U8_U8_U8_U8))
     BV_FLOAT_SET (f32, ieee_single, float, 4);
 
-  VM_DEFINE_OP (121, bv_f64_set, "bv-f64-set!", OP1 (U8_U8_U8_U8))
+  VM_DEFINE_OP (122, bv_f64_set, "bv-f64-set!", OP1 (U8_U8_U8_U8))
     BV_FLOAT_SET (f64, ieee_double, double, 8);
 
   END_DISPATCH_SWITCH;
diff --git a/module/language/cps/compile-rtl.scm b/module/language/cps/compile-rtl.scm
index 88c9a4430..039eb8c09 100644
--- a/module/language/cps/compile-rtl.scm
+++ b/module/language/cps/compile-rtl.scm
@@ -186,6 +186,14 @@
            (emit-resolve asm dst (constant bound?) (slot name)))
           (($ $primcall 'free-ref (closure idx))
            (emit-free-ref asm dst (slot closure) (constant idx)))
+          (($ $primcall 'vector-ref (vector index))
+           (call-with-values (lambda ()
+                               (lookup-maybe-constant-value index allocation))
+             (lambda (has-const? index-val)
+               (if (and has-const? (integer? index-val) (exact? index-val)
+                        (<= 0 index-val 255))
+                   (emit-constant-vector-ref asm dst (slot vector) index-val)
+                   (emit-vector-ref asm dst (slot vector) (slot index))))))
           (($ $primcall name args)
            ;; FIXME: Inline all the cases.
            (let ((inst (prim-rtl-instruction name)))
@@ -217,7 +225,15 @@
         (($ $primcall 'struct-set! (struct index value))
          (emit-struct-set! asm (slot struct) (slot index) (slot value)))
         (($ $primcall 'vector-set! (vector index value))
-         (emit-vector-set! asm (slot vector) (slot index) (slot value)))
+         (call-with-values (lambda ()
+                             (lookup-maybe-constant-value index allocation))
+           (lambda (has-const? index-val)
+             (if (and has-const? (integer? index-val) (exact? index-val)
+                      (<= 0 index-val 255))
+                 (emit-constant-vector-set! asm (slot vector) index-val
+                                            (slot value))
+                 (emit-vector-set! asm (slot vector) (slot index)
+                                   (slot value))))))
         (($ $primcall 'variable-set! (var val))
          (emit-box-set! asm (slot var) (slot val)))
         (($ $primcall 'set-car! (pair value))
diff --git a/module/language/cps/dfg.scm b/module/language/cps/dfg.scm
index e56c986b6..4b53ab24d 100644
--- a/module/language/cps/dfg.scm
+++ b/module/language/cps/dfg.scm
@@ -801,6 +801,12 @@
               #f)
              (($ $primcall 'resolve (name bound?))
               (eq? sym name))
+             (($ $primcall 'vector-ref (v i))
+              (not (and (eq? sym i)
+                        (integer? val) (exact? val) (<= 0 val 255))))
+             (($ $primcall 'vector-set! (v i x))
+              (not (and (eq? sym i)
+                        (integer? val) (exact? val) (<= 0 val 255))))
              (_ #t)))
          uses))))))