diff --git a/py/objstr.c b/py/objstr.c
index 54dd087a45..8e3e9d9025 100644
--- a/py/objstr.c
+++ b/py/objstr.c
@@ -35,6 +35,7 @@ mp_obj_t str_binary_op(int op, mp_obj_t lhs_in, mp_obj_t rhs_in) {
             if (MP_OBJ_IS_SMALL_INT(rhs_in)) {
                 // TODO: This implements byte string access for single index so far
                 return mp_obj_new_int(lhs_str[mp_obj_get_int(rhs_in)]);
+#if MICROPY_ENABLE_SLICE
             } else if (MP_OBJ_IS_TYPE(rhs_in, &slice_type)) {
                 int start, stop, step;
                 mp_obj_slice_get(rhs_in, &start, &stop, &step);
@@ -47,6 +48,7 @@ mp_obj_t str_binary_op(int op, mp_obj_t lhs_in, mp_obj_t rhs_in) {
                     stop = len + stop;
                 }
                 return mp_obj_new_str(qstr_from_strn_copy(lhs_str + start, stop - start));
+#endif
             } else {
                 // Throw TypeError here
                 assert(0);
diff --git a/py/vm.c b/py/vm.c
index 35dcbea523..382780640b 100644
--- a/py/vm.c
+++ b/py/vm.c
@@ -410,6 +410,7 @@ bool mp_execute_byte_code_2(const byte **ip_in_out, mp_obj_t *fastn, mp_obj_t **
                         sp++;
                         break;
 
+#if MICROPY_ENABLE_SLICE
                     case MP_BC_BUILD_SLICE:
                         DECODE_UINT;
                         if (unum == 2) {
@@ -421,6 +422,7 @@ bool mp_execute_byte_code_2(const byte **ip_in_out, mp_obj_t *fastn, mp_obj_t **
                             assert(0);
                         }
                         break;
+#endif
 
                     case MP_BC_UNPACK_SEQUENCE:
                         DECODE_UINT;