encode.patch

diff --git a/src/6model/reprs/VMArray.c b/src/6model/reprs/VMArray.c
index 7f5f79b99..03374c67a 100644
--- a/src/6model/reprs/VMArray.c
+++ b/src/6model/reprs/VMArray.c
@@ -986,8 +986,11 @@ static void asplice(MVMThreadContext *tc, MVMSTable *st, MVMObject *root, void *
             tail * repr_data->elem_size);
     }
 
+    fprintf(stderr, "\n%s\n", MVM_exception_backtrace_line(tc, tc->cur_frame, 0, *(tc->interp_cur_op)));
+    MVMuint64 e = body->elems, s = body->start, ss = body->ssize;
     /* now resize the array */
     set_size_internal(tc, body, offset + elems1 + tail, repr_data);
+    fprintf(stderr, "increased by: elems = %lu, start = %lu, ssize = %lu\n\n", body->elems - e, body->start - s, body->ssize - ss);
 
     start = body->start;
     if (tail > 0 && count < elems1) {
diff --git a/src/strings/ops.c b/src/strings/ops.c
index a59bad6bd..ed828f4ac 100644
--- a/src/strings/ops.c
+++ b/src/strings/ops.c
@@ -1785,8 +1785,6 @@ MVMObject * MVM_string_encode_to_buf_config(MVMThreadContext *tc, MVMString *s,
     }
     if (!elem_size)
         MVM_exception_throw_adhoc(tc, "encode requires a native int array");
-    if (((MVMArray *)buf)->body.slots.any)
-        MVM_exception_throw_adhoc(tc, "encode requires an empty array");
 
     /* At least find_encoding may allocate on first call, so root just
      * in case. */
@@ -1797,10 +1795,18 @@ MVMObject * MVM_string_encode_to_buf_config(MVMThreadContext *tc, MVMString *s,
     });
 
     /* Stash the encoded data in the VMArray. */
-    ((MVMArray *)buf)->body.slots.i8 = (MVMint8 *)encoded;
-    ((MVMArray *)buf)->body.start    = 0;
-    ((MVMArray *)buf)->body.ssize    = output_size / elem_size;
-    ((MVMArray *)buf)->body.elems    = output_size / elem_size;
+    if (((MVMArray *)buf)->body.slots.any) {
+        MVMuint32 prev_elems = ((MVMArray *)buf)->body.elems;
+        MVM_repr_pos_set_elems(tc, buf, ((MVMArray *)buf)->body.elems + output_size / elem_size);
+        memmove(((MVMArray *)buf)->body.slots.i8 + prev_elems, (MVMint8 *)encoded, output_size);
+    }
+    else {
+        ((MVMArray *)buf)->body.slots.i8 = (MVMint8 *)encoded;
+        ((MVMArray *)buf)->body.start    = 0;
+        ((MVMArray *)buf)->body.ssize    = output_size / elem_size;
+        ((MVMArray *)buf)->body.elems    = output_size / elem_size;
+    }
+
     return buf;
 }
 MVMObject * MVM_string_encode_to_buf(MVMThreadContext *tc, MVMString *s, MVMString *enc_name,

string_heap.patch

diff --git a/src/vm/moar/QAST/QASTCompilerMAST.nqp b/src/vm/moar/QAST/QASTCompilerMAST.nqp
index 712289781..0950d8491 100644
--- a/src/vm/moar/QAST/QASTCompilerMAST.nqp
+++ b/src/vm/moar/QAST/QASTCompilerMAST.nqp
@@ -2302,13 +2302,14 @@ class MoarVM::StringHeap {
             $utf8 := 1 if $g < 0 || $g >= 0xff || $g == 0x0d;
         }
 
-        my $encoded := nqp::encode($s, ($utf8 ?? "utf8" !! "iso-8859-1"), nqp::create(MAST::Bytecode));
-        my int $encoded_size := nqp::elems($encoded);
+        my int $prev_total_size := nqp::elems($!strings);
+        nqp::setelems($!strings, $prev_total_size + 4);
+        nqp::encode($s, ($utf8 ?? "utf8" !! "iso-8859-1"), $!strings);
+        my int $encoded_size := nqp::elems($!strings) - 4 - $prev_total_size;
         my int $pad := 4 - $encoded_size % 4;
         $pad := 0 if $pad == 4;
 
-        $!strings.write_uint32($encoded_size * 2 + $utf8); # LSB is UTF-8 flag
-        $!strings.write_buf($encoded);
+        $!strings.write_uint32_at($encoded_size * 2 + $utf8, $prev_total_size); # LSB is UTF-8 flag
         $!strings.write_uint8(0) while $pad--;
 
         nqp::push_s(@!orig-strings, $s);