diff --git a/src/hb-wasm-api-buffer.hh b/src/hb-wasm-api-buffer.hh
index 3164b7617..a5560bc25 100644
--- a/src/hb-wasm-api-buffer.hh
+++ b/src/hb-wasm-api-buffer.hh
@@ -51,6 +51,38 @@ buffer_contents_free (HB_WASM_EXEC_ENV
   contents->length = 0;
 }
 
+void
+ buffer_contents_realloc (HB_WASM_EXEC_ENV
+			  ptr_t(buffer_contents_t) contentsptr,
+			  uint32_t size)
+{
+  HB_STRUCT_TYPE (buffer_contents_t, contents);
+  if (unlikely (!contents))
+    return;
+
+  if (size <= contents->length)
+    return;
+
+  unsigned bytes;
+  if (hb_unsigned_mul_overflows (size, sizeof (glyph_info_t), &bytes))
+    return;
+
+  // TODO bounds check?
+  uint32_t infoptr = contents->info;
+  uint32_t posptr = contents->pos;
+  const char *info = (const char *) addr_app_to_native (infoptr);
+  const char *pos = (const char *) addr_app_to_native (posptr);
+
+  contents->info = wasm_runtime_module_dup_data (module_inst, info, bytes);
+  contents->pos = wasm_runtime_module_dup_data (module_inst, pos, bytes);
+
+  module_free (infoptr);
+  module_free (posptr);
+
+  // TODO Check success
+  contents->length = size;
+}
+
 void
 buffer_copy_contents (HB_WASM_EXEC_ENV_COMPOUND
 		      ptr_t(buffer_t) bufferref)
@@ -67,7 +99,6 @@ buffer_copy_contents (HB_WASM_EXEC_ENV_COMPOUND
   ret.pos = wasm_runtime_module_dup_data (module_inst, (const char *) buffer->pos, length * sizeof (buffer->pos[0]));
 }
 
-
 bool_t
 buffer_set_contents (HB_WASM_EXEC_ENV
 		     ptr_t(buffer_t) bufferref,
diff --git a/src/hb-wasm-api-list.hh b/src/hb-wasm-api-list.hh
index dc29b2f8f..cb60ee76a 100644
--- a/src/hb-wasm-api-list.hh
+++ b/src/hb-wasm-api-list.hh
@@ -56,6 +56,7 @@ static NativeSymbol _hb_wasm_native_symbols[] =
 
   /* buffer */
   NATIVE_SYMBOL ("(i)",		buffer_contents_free),
+  NATIVE_SYMBOL ("(ii)",	buffer_contents_realloc),
   NATIVE_SYMBOL ("(ii)",	buffer_copy_contents),
   NATIVE_SYMBOL ("(ii)i",	buffer_set_contents),
 
diff --git a/src/hb-wasm-api.h b/src/hb-wasm-api.h
index e5f6700d1..405189ed3 100644
--- a/src/hb-wasm-api.h
+++ b/src/hb-wasm-api.h
@@ -115,6 +115,10 @@ typedef struct
   ptr_t(glyph_position_t) pos;
 } buffer_contents_t;
 
+HB_WASM_API (void, buffer_contents_realloc) (HB_WASM_EXEC_ENV
+					     ptr_t(buffer_contents_t),
+					     uint32_t size);
+
 HB_WASM_API (void, buffer_contents_free) (HB_WASM_EXEC_ENV
 					  ptr_t(buffer_contents_t));
 
diff --git a/src/wasm-graphite/shape.cc b/src/wasm-graphite/shape.cc
index 546cfd5dc..963a00651 100644
--- a/src/wasm-graphite/shape.cc
+++ b/src/wasm-graphite/shape.cc
@@ -78,8 +78,7 @@ shape (font_t *font, buffer_t *buffer)
   };
 
   length = glyph_count;
-  //contents.info = (glyph_info_t *) realloc (contents.info, length * sizeof (glyph_info_t));
-  //contents.pos = (glyph_position_t *) realloc (contents.pos, length * sizeof (glyph_position_t));
+  buffer_contents_realloc (&contents, length);
   cluster_t *clusters = (cluster_t *) malloc (length * sizeof (cluster_t));
   uint32_t *gids = (uint32_t *) malloc (length * sizeof (uint32_t));