diff --git a/src/hb-ot-layout-gpos-table.hh b/src/hb-ot-layout-gpos-table.hh
index d8e3e6e..8e2860c 100644
--- a/src/hb-ot-layout-gpos-table.hh
+++ b/src/hb-ot-layout-gpos-table.hh
@@ -1589,6 +1589,8 @@
 void
 GPOS::position_finish (hb_font_t *font HB_UNUSED, hb_buffer_t *buffer)
 {
+  _hb_buffer_assert_gsubgpos_vars (buffer);
+
   unsigned int len;
   hb_glyph_position_t *pos = hb_buffer_get_glyph_positions (buffer, &len);
   hb_direction_t direction = buffer->props.direction;
@@ -1600,8 +1602,6 @@
   /* Handle attachments */
   for (unsigned int i = 0; i < len; i++)
     fix_mark_attachment (pos, i, direction);
-
-  _hb_buffer_deallocate_gsubgpos_vars (buffer);
 }
 
 
diff --git a/src/hb-ot-layout-gsub-table.hh b/src/hb-ot-layout-gsub-table.hh
index e193973..2b421a9 100644
--- a/src/hb-ot-layout-gsub-table.hh
+++ b/src/hb-ot-layout-gsub-table.hh
@@ -1338,7 +1338,7 @@
 void
 GSUB::substitute_start (hb_font_t *font, hb_buffer_t *buffer)
 {
-  _hb_buffer_allocate_gsubgpos_vars (buffer);
+  _hb_buffer_assert_gsubgpos_vars (buffer);
 
   const GDEF &gdef = *hb_ot_layout_from_face (font->face)->gdef;
   unsigned int count = buffer->len;
diff --git a/src/hb-ot-layout-private.hh b/src/hb-ot-layout-private.hh
index d94ac50..ae7daa6 100644
--- a/src/hb-ot-layout-private.hh
+++ b/src/hb-ot-layout-private.hh
@@ -420,6 +420,13 @@
 }
 
 static inline void
+_hb_buffer_assert_unicode_vars (hb_buffer_t *buffer)
+{
+  HB_BUFFER_ASSERT_VAR (buffer, unicode_props0);
+  HB_BUFFER_ASSERT_VAR (buffer, unicode_props1);
+}
+
+static inline void
 _hb_buffer_allocate_gsubgpos_vars (hb_buffer_t *buffer)
 {
   HB_BUFFER_ALLOCATE_VAR (buffer, glyph_props);
@@ -435,6 +442,14 @@
   HB_BUFFER_DEALLOCATE_VAR (buffer, glyph_props);
 }
 
+static inline void
+_hb_buffer_assert_gsubgpos_vars (hb_buffer_t *buffer)
+{
+  HB_BUFFER_ASSERT_VAR (buffer, glyph_props);
+  HB_BUFFER_ASSERT_VAR (buffer, lig_props);
+  HB_BUFFER_ASSERT_VAR (buffer, syllable);
+}
+
 /* Make sure no one directly touches our props... */
 #undef unicode_props0
 #undef unicode_props1
diff --git a/src/hb-ot-shape-complex-arabic-fallback.hh b/src/hb-ot-shape-complex-arabic-fallback.hh
index e62cea4..e5b7ed4 100644
--- a/src/hb-ot-shape-complex-arabic-fallback.hh
+++ b/src/hb-ot-shape-complex-arabic-fallback.hh
@@ -271,7 +271,7 @@
 				   const hb_ot_shape_plan_t *plan,
 				   hb_font_t *font)
 {
-  ASSERT_STATIC (ARRAY_LENGTH(arabic_fallback_features) <= ARABIC_FALLBACK_MAX_LOOKUPS);
+  ASSERT_STATIC (ARRAY_LENGTH_CONST(arabic_fallback_features) <= ARABIC_FALLBACK_MAX_LOOKUPS);
   unsigned int j = 0;
   for (unsigned int i = 0; i < ARRAY_LENGTH(arabic_fallback_features) ; i++)
   {
diff --git a/src/hb-ot-shape-fallback.cc b/src/hb-ot-shape-fallback.cc
index a774f95..80d7da8 100644
--- a/src/hb-ot-shape-fallback.cc
+++ b/src/hb-ot-shape-fallback.cc
@@ -415,6 +415,8 @@
 				hb_font_t *font,
 				hb_buffer_t  *buffer)
 {
+  _hb_buffer_assert_gsubgpos_vars (buffer);
+
   unsigned int start = 0;
   unsigned int last_cluster = buffer->info[0].cluster;
   unsigned int count = buffer->len;
diff --git a/src/hb-ot-shape-normalize.cc b/src/hb-ot-shape-normalize.cc
index 2a6a439..4287253 100644
--- a/src/hb-ot-shape-normalize.cc
+++ b/src/hb-ot-shape-normalize.cc
@@ -289,6 +289,8 @@
 			hb_buffer_t *buffer,
 			hb_font_t *font)
 {
+  _hb_buffer_assert_unicode_vars (buffer);
+
   hb_ot_shape_normalization_mode_t mode = plan->shaper->normalization_preference;
   const hb_ot_shape_normalize_context_t c = {
     plan,
diff --git a/src/hb-ot-shape.cc b/src/hb-ot-shape.cc
index 0933ca2..a0b503a 100644
--- a/src/hb-ot-shape.cc
+++ b/src/hb-ot-shape.cc
@@ -448,6 +448,7 @@
 {
   hb_buffer_t *buffer = c->buffer;
 
+  _hb_buffer_allocate_gsubgpos_vars (buffer);
   hb_ot_layout_substitute_start (c->font, buffer);
 
   if (!hb_ot_layout_has_glyph_classes (c->face))
@@ -636,6 +637,8 @@
 
   if (fallback)
     _hb_ot_shape_fallback_kern (c->plan, c->font, c->buffer);
+
+  _hb_buffer_deallocate_gsubgpos_vars (c->buffer);
 }