diff --git a/src/hb-ot-color-sbix-table.hh b/src/hb-ot-color-sbix-table.hh
index 726356a59..c2a53e137 100644
--- a/src/hb-ot-color-sbix-table.hh
+++ b/src/hb-ot-color-sbix-table.hh
@@ -339,20 +339,16 @@ struct sbix
 			  strikes.sanitize (c, this)));
   }
 
-  bool add_strike (hb_subset_context_t *c,
-		   const void *dst_base,
-		   unsigned int i,
-		   unsigned int sbix_len) const {
-    if (strikes[i].is_null () ||
-	sbix_len < (unsigned int) strikes[i])
+  bool
+  add_strike (hb_subset_context_t *c, const void *dst_base, unsigned i) const
+  {
+    if (strikes[i].is_null () || c->source_blob->length < (unsigned) strikes[i])
       return false;
 
-    return (this+strikes[i]).subset (c, sbix_len - (unsigned int) strikes[i]);
+    return (this+strikes[i]).subset (c, c->source_blob->length - (unsigned) strikes[i]);
   }
 
-  bool serialize_strike_offsets (hb_subset_context_t *c,
-				 const void *dst_base,
-				 unsigned int sbix_len) const
+  bool serialize_strike_offsets (hb_subset_context_t *c, const void *dst_base) const
   {
     TRACE_SERIALIZE (this);
 
@@ -369,7 +365,7 @@ struct sbix
       *o = 0;
       auto snap = c->serializer->snapshot ();
       c->serializer->push ();
-      bool ret = add_strike (c, dst_base, i, sbix_len);
+      bool ret = add_strike (c, dst_base, i);
       if (!ret)
       {
 	c->serializer->pop_discard ();
@@ -396,11 +392,8 @@ struct sbix
     if (unlikely (!sbix_prime)) return_trace (false);
     if (unlikely (!c->serializer->embed (this->version))) return_trace (false);
     if (unlikely (!c->serializer->embed (this->flags))) return_trace (false);
-    hb_blob_ptr_t<sbix> table = hb_sanitize_context_t ().reference_table<sbix> (c->plan->source);
-    const unsigned int sbix_len = table.get_blob ()->length;
-    table.destroy ();
 
-    return_trace (serialize_strike_offsets (c, sbix_prime, sbix_len));
+    return_trace (serialize_strike_offsets (c, sbix_prime));
   }
 
   protected:
diff --git a/src/hb-ot-var-gvar-table.hh b/src/hb-ot-var-gvar-table.hh
index e8f24a135..633e4d071 100644
--- a/src/hb-ot-var-gvar-table.hh
+++ b/src/hb-ot-var-gvar-table.hh
@@ -409,25 +409,19 @@ struct gvar
     unsigned int num_glyphs = c->plan->num_output_glyphs ();
     out->glyphCount = num_glyphs;
 
-    hb_blob_ptr_t<gvar> table = hb_sanitize_context_t ().reference_table<gvar> (c->plan->source);
-
     unsigned int subset_data_size = 0;
     for (hb_codepoint_t gid = 0; gid < num_glyphs; gid++)
     {
       hb_codepoint_t old_gid;
       if (!c->plan->old_gid_for_new_gid (gid, &old_gid)) continue;
-      subset_data_size += get_glyph_var_data_bytes (table.get_blob (), old_gid).length;
+      subset_data_size += get_glyph_var_data_bytes (c->source_blob, old_gid).length;
     }
 
     bool long_offset = subset_data_size & ~0xFFFFu;
     out->flags = long_offset ? 1 : 0;
 
     HBUINT8 *subset_offsets = c->serializer->allocate_size<HBUINT8> ((long_offset ? 4 : 2) * (num_glyphs + 1));
-    if (!subset_offsets)
-    {
-      table.destroy ();
-      return_trace (false);
-    }
+    if (!subset_offsets) return_trace (false);
 
     /* shared tuples */
     if (!sharedTupleCount || !sharedTuples)
@@ -436,29 +430,21 @@ struct gvar
     {
       unsigned int shared_tuple_size = F2DOT14::static_size * axisCount * sharedTupleCount;
       F2DOT14 *tuples = c->serializer->allocate_size<F2DOT14> (shared_tuple_size);
-      if (!tuples)
-      {
-	table.destroy ();
-	return_trace (false);
-      }
+      if (!tuples) return_trace (false);
       out->sharedTuples = (char *) tuples - (char *) out;
       memcpy (tuples, &(this+sharedTuples), shared_tuple_size);
     }
 
     char *subset_data = c->serializer->allocate_size<char> (subset_data_size);
-    if (!subset_data)
-    {
-      table.destroy ();
-      return_trace (false);
-    }
-    out->dataZ = subset_data - (char *)out;
+    if (!subset_data) return_trace (false);
+    out->dataZ = subset_data - (char *) out;
 
     unsigned int glyph_offset = 0;
     for (hb_codepoint_t gid = 0; gid < num_glyphs; gid++)
     {
       hb_codepoint_t old_gid;
       hb_bytes_t var_data_bytes = c->plan->old_gid_for_new_gid (gid, &old_gid)
-				? get_glyph_var_data_bytes (table.get_blob (), old_gid)
+				? get_glyph_var_data_bytes (c->source_blob, old_gid)
 				: hb_bytes_t ();
 
       if (long_offset)
@@ -476,7 +462,6 @@ struct gvar
     else
       ((HBUINT16 *) subset_offsets)[num_glyphs] = glyph_offset / 2;
 
-    table.destroy ();
     return_trace (true);
   }
 
diff --git a/src/hb-subset.cc b/src/hb-subset.cc
index 6bcc0b023..a03b41f14 100644
--- a/src/hb-subset.cc
+++ b/src/hb-subset.cc
@@ -89,7 +89,7 @@ _subset (hb_subset_plan_t *plan)
   retry:
     hb_serialize_context_t serializer ((void *) buf, buf_size);
     serializer.start_serialize<TableType> ();
-    hb_subset_context_t c (plan, &serializer);
+    hb_subset_context_t c (source_blob, plan, &serializer);
     bool needed = table->subset (&c);
     if (serializer.ran_out_of_room)
     {
diff --git a/src/hb-subset.hh b/src/hb-subset.hh
index b8dd07ab2..64d725362 100644
--- a/src/hb-subset.hh
+++ b/src/hb-subset.hh
@@ -54,12 +54,15 @@ struct hb_subset_context_t :
   dispatch (const T &obj, Ts&&... ds) HB_AUTO_RETURN
   ( _dispatch (obj, hb_prioritize, hb_forward<Ts> (ds)...) )
 
+  hb_blob_t *source_blob;
   hb_subset_plan_t *plan;
   hb_serialize_context_t *serializer;
   unsigned int debug_depth;
 
-  hb_subset_context_t (hb_subset_plan_t *plan_,
+  hb_subset_context_t (hb_blob_t *source_blob_,
+		       hb_subset_plan_t *plan_,
 		       hb_serialize_context_t *serializer_) :
+		        source_blob (source_blob_),
 			plan (plan_),
 			serializer (serializer_),
 			debug_depth (0) {}