diff --git a/src/hb-ot-var-common.hh b/src/hb-ot-var-common.hh
index 01930a8e9..5c82ae159 100644
--- a/src/hb-ot-var-common.hh
+++ b/src/hb-ot-var-common.hh
@@ -270,7 +270,7 @@ struct TupleVariationHeader
 
       if (shared_tuple_active_idx)
       {
-	int v = (*shared_tuple_active_idx)[index];
+	int v = (*shared_tuple_active_idx).arrayZ[index];
 	if (v != -1)
 	{
 	  start_idx = v;
diff --git a/src/hb-ot-var-gvar-table.hh b/src/hb-ot-var-gvar-table.hh
index 7a8599a7c..0ca7192a2 100644
--- a/src/hb-ot-var-gvar-table.hh
+++ b/src/hb-ot-var-gvar-table.hh
@@ -227,7 +227,7 @@ struct gvar
 
       hb_array_t<const F2DOT14> shared_tuples = (table+table->sharedTuples).as_array (table->sharedTupleCount * table->axisCount);
       unsigned count = table->sharedTupleCount;
-      shared_tuple_active_idx.resize (count);
+      if (unlikely (!shared_tuple_active_idx.resize (count, false))) return;
       unsigned axis_count = table->axisCount;
       for (unsigned i = 0; i < count; i++)
       {
@@ -316,7 +316,8 @@ struct gvar
       bool flush = false;
       do
       {
-	float scalar = iterator.current_tuple->calculate_scalar (coords, num_coords, shared_tuples, &shared_tuple_active_idx);
+	float scalar = iterator.current_tuple->calculate_scalar (coords, num_coords, shared_tuples,
+								 shared_tuple_active_idx.in_error () ? nullptr : &shared_tuple_active_idx);
 	if (scalar == 0.f) continue;
 	const HBUINT8 *p = iterator.get_serialized_data ();
 	unsigned int length = iterator.current_tuple->get_data_size ();