diff --git a/src/hb-aat-layout-lcar-table.hh b/src/hb-aat-layout-lcar-table.hh
index e57836a08..43ac74f9c 100644
--- a/src/hb-aat-layout-lcar-table.hh
+++ b/src/hb-aat-layout-lcar-table.hh
@@ -49,7 +49,8 @@ struct lcar
 				      unsigned int   *caret_count /* IN/OUT */,
 				      hb_position_t  *caret_array /* OUT */) const
   {
-    const OffsetTo<LigCaretClassEntry>* entry_offset = lookup.get_value (glyph, font->face->num_glyphs);
+    const OffsetTo<LigCaretClassEntry>* entry_offset = lookup.get_value (glyph,
+									 font->face->get_num_glyphs ());
     const LigCaretClassEntry& array = entry_offset ? this+*entry_offset : Null (LigCaretClassEntry);
     if (caret_count && *caret_count)
     {
diff --git a/src/hb-face.cc b/src/hb-face.cc
index da73433cb..3294ed4c4 100644
--- a/src/hb-face.cc
+++ b/src/hb-face.cc
@@ -87,8 +87,8 @@ DEFINE_NULL_INSTANCE (hb_face_t) =
   nullptr, /* destroy */
 
   0,    /* index */
-  1000, /* upem */
-  0,    /* num_glyphs */
+  HB_ATOMIC_INT_INIT (1000), /* upem */
+  HB_ATOMIC_INT_INIT (0),    /* num_glyphs */
 
   {
 #define HB_SHAPER_IMPLEMENT(shaper) HB_ATOMIC_PTR_INIT (HB_SHAPER_DATA_INVALID),
@@ -129,7 +129,7 @@ hb_face_create_for_tables (hb_reference_table_func_t  reference_table_func,
   face->user_data = user_data;
   face->destroy = destroy;
 
-  face->num_glyphs = (unsigned int) -1;
+  face->num_glyphs.set_relaxed (-1);
 
   face->table.init0 (face);
 
@@ -445,7 +445,7 @@ hb_face_set_upem (hb_face_t    *face,
   if (hb_object_is_immutable (face))
     return;
 
-  face->upem = upem;
+  face->upem.set_relaxed (upem);
 }
 
 /**
@@ -480,7 +480,7 @@ hb_face_set_glyph_count (hb_face_t    *face,
   if (hb_object_is_immutable (face))
     return;
 
-  face->num_glyphs = glyph_count;
+  face->num_glyphs.set_relaxed (glyph_count);
 }
 
 /**
diff --git a/src/hb-face.hh b/src/hb-face.hh
index 5d22f4ada..002fb2cb7 100644
--- a/src/hb-face.hh
+++ b/src/hb-face.hh
@@ -49,8 +49,8 @@ struct hb_face_t
   hb_destroy_func_t          destroy;
 
   unsigned int index;			/* Face index in a collection, zero-based. */
-  mutable unsigned int upem;		/* Units-per-EM. */
-  mutable unsigned int num_glyphs;	/* Number of glyphs. */
+  mutable hb_atomic_int_t upem;		/* Units-per-EM. */
+  mutable hb_atomic_int_t num_glyphs;	/* Number of glyphs. */
 
   struct hb_shaper_data_t shaper_data;	/* Various shaper data. */
 
@@ -80,21 +80,25 @@ struct hb_face_t
 
   inline HB_PURE_FUNC unsigned int get_upem (void) const
   {
-    if (unlikely (!upem))
-      load_upem ();
-    return upem;
+    unsigned int ret = upem.get_relaxed ();
+    if (unlikely (!ret))
+    {
+      return load_upem ();
+    }
+    return ret;
   }
 
   inline unsigned int get_num_glyphs (void) const
   {
-    if (unlikely (num_glyphs == (unsigned int) -1))
-      load_num_glyphs ();
-    return num_glyphs;
+    unsigned int ret = num_glyphs.get_relaxed ();
+    if (unlikely (ret == (unsigned int) -1))
+      return load_num_glyphs ();
+    return ret;
   }
 
   private:
-  HB_INTERNAL void load_upem (void) const;
-  HB_INTERNAL void load_num_glyphs (void) const;
+  HB_INTERNAL unsigned int load_upem (void) const;
+  HB_INTERNAL unsigned int load_num_glyphs (void) const;
 };
 DECLARE_NULL_INSTANCE (hb_face_t);
 
diff --git a/src/hb-ot-color-sbix-table.hh b/src/hb-ot-color-sbix-table.hh
index 80d65022c..08dee2a0c 100644
--- a/src/hb-ot-color-sbix-table.hh
+++ b/src/hb-ot-color-sbix-table.hh
@@ -249,7 +249,7 @@ struct sbix
       /* Convert to font units. */
       if (strike_ppem)
       {
-	double scale = font->face->upem / (double) strike_ppem;
+	double scale = font->face->get_upem () / (double) strike_ppem;
 	extents->x_bearing = round (extents->x_bearing * scale);
 	extents->y_bearing = round (extents->y_bearing * scale);
 	extents->width = round (extents->width * scale);
diff --git a/src/hb-static.cc b/src/hb-static.cc
index 461b08be5..73d9528e6 100644
--- a/src/hb-static.cc
+++ b/src/hb-static.cc
@@ -46,21 +46,26 @@ DEFINE_NULL_NAMESPACE_BYTES (OT, RangeRecord) = {0x00,0x01, 0x00,0x00, 0x00, 0x0
 const unsigned char _hb_Null_AAT_Lookup[2] = {0xFF, 0xFF};
 
 
-void
+unsigned int
 hb_face_t::load_num_glyphs (void) const
 {
   hb_sanitize_context_t c = hb_sanitize_context_t ();
   c.set_num_glyphs (0); /* So we don't recurse ad infinitum. */
   hb_blob_t *maxp_blob = c.reference_table<OT::maxp> (this);
   const OT::maxp *maxp_table = maxp_blob->as<OT::maxp> ();
-  num_glyphs = maxp_table->get_num_glyphs ();
+
+  unsigned int ret = maxp_table->get_num_glyphs ();
+  num_glyphs.set_relaxed (ret);
   hb_blob_destroy (maxp_blob);
+  return ret;
 }
 
-void
+unsigned int
 hb_face_t::load_upem (void) const
 {
-  upem = table.head->get_upem ();
+  unsigned int ret = table.head->get_upem ();
+  upem.set_relaxed (ret);
+  return ret;
 }
 
 #endif