diff --git a/test/api/Makefile.am b/test/api/Makefile.am
index d92e96694..1c0f92c13 100644
--- a/test/api/Makefile.am
+++ b/test/api/Makefile.am
@@ -76,6 +76,12 @@ TEST_PROGS += \
 	test-ot-tag \
 	$(NULL)
 
+if HAVE_PTHREAD
+TEST_PROGS += test-multithread
+test_multithread_CFLAGS = $(CFLAGS) $(PTHREAD_CFLAGS)
+test_multithread_LDADD = $(LDADD) $(PTHREAD_LIBS)
+endif
+
 if HAVE_FREETYPE
 TEST_PROGS += \
 	test-ot-math \
diff --git a/test/api/test-multithread.c b/test/api/test-multithread.c
new file mode 100644
index 000000000..3a0d8845d
--- /dev/null
+++ b/test/api/test-multithread.c
@@ -0,0 +1,146 @@
+/*
+ * Copyright © 2018  Ebrahim Byagowi
+ *
+ *  This is part of HarfBuzz, a text shaping library.
+ *
+ * Permission is hereby granted, without written agreement and without
+ * license or royalty fees, to use, copy, modify, and distribute this
+ * software and its documentation for any purpose, provided that the
+ * above copyright notice and the following two paragraphs appear in
+ * all copies of this software.
+ *
+ * IN NO EVENT SHALL THE COPYRIGHT HOLDER BE LIABLE TO ANY PARTY FOR
+ * DIRECT, INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES
+ * ARISING OUT OF THE USE OF THIS SOFTWARE AND ITS DOCUMENTATION, EVEN
+ * IF THE COPYRIGHT HOLDER HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH
+ * DAMAGE.
+ *
+ * THE COPYRIGHT HOLDER SPECIFICALLY DISCLAIMS ANY WARRANTIES, INCLUDING,
+ * BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
+ * FITNESS FOR A PARTICULAR PURPOSE.  THE SOFTWARE PROVIDED HEREUNDER IS
+ * ON AN "AS IS" BASIS, AND THE COPYRIGHT HOLDER HAS NO OBLIGATION TO
+ * PROVIDE MAINTENANCE, SUPPORT, UPDATES, ENHANCEMENTS, OR MODIFICATIONS.
+ *
+ */
+
+#include <stdlib.h>
+#include <string.h>
+#include <stdio.h>
+
+#include <pthread.h>
+
+#include <hb.h>
+#include <hb-ot.h>
+
+const char *text = "طرح‌نَما";
+const char *path =
+#if defined(__linux__)
+		"/usr/share/fonts/truetype/dejavu/DejaVuSans.ttf";
+#elif defined(_WIN32) || defined(_WIN64)
+		"C:\\Windows\\Fonts\\tahoma.ttf";
+#elif __APPLE__
+		"/Library/Fonts/Tahoma.ttf";
+#endif
+
+int num_iters = 200;
+
+hb_font_t *font;
+
+pthread_mutex_t mutex = PTHREAD_MUTEX_INITIALIZER;
+
+static void
+fill_the_buffer(hb_buffer_t *buffer)
+{
+  hb_buffer_add_utf8 (buffer, text, sizeof (text), 0, sizeof (text));
+  hb_buffer_guess_segment_properties (buffer);
+  hb_shape (font, buffer, NULL, 0);
+}
+
+static void *
+thread_func (void *data)
+{
+  hb_buffer_t *buffer = (hb_buffer_t *) data;
+
+  pthread_mutex_lock (&mutex);
+  pthread_mutex_unlock (&mutex);
+
+  int i;
+  for (i = 0; i < num_iters; i++)
+  {
+    hb_buffer_clear_contents (buffer);
+    fill_the_buffer (buffer);
+  }
+
+  return 0;
+}
+
+int
+main (int argc, char **argv)
+{
+  int i;
+  int num_threads = 1; // FIXME: Increase this and fix the issue
+  pthread_t *threads = calloc (num_threads, sizeof (pthread_t));
+  hb_buffer_t **buffers = calloc (num_threads, sizeof (hb_buffer_t *));
+
+  pthread_mutex_lock (&mutex);
+
+  hb_blob_t *blob = hb_blob_create_from_file (path);
+  hb_face_t *face = hb_face_create (blob, 0);
+  font = hb_font_create (face);
+  hb_ot_font_set_funcs (font);
+
+  for (i = 0; i < num_threads; i++)
+  {
+    hb_buffer_t *buffer = hb_buffer_create ();
+    buffers[i] = buffer;
+    pthread_create (&threads[i], NULL, thread_func, buffer);
+  }
+
+  /* Let them loose! */
+  pthread_mutex_unlock (&mutex);
+
+  for (i = 0; i < num_threads; i++)
+  {
+    pthread_join (threads[i], NULL);
+
+    hb_buffer_t *ref_buffer = hb_buffer_create ();
+    fill_the_buffer (ref_buffer);
+
+    for (i = 0; i < num_threads; i++)
+    {
+      hb_buffer_t *buffer = buffers[i];
+      hb_buffer_diff_flags_t diff = hb_buffer_diff (ref_buffer, buffer, (hb_codepoint_t) -1, 0);
+      if (diff)
+      {
+	fprintf (stderr, "One of the buffers (%d) was different from the reference.\n", i);
+	char out[255];
+
+	hb_buffer_serialize_glyphs (buffer, 0, hb_buffer_get_length (ref_buffer),
+				    out, sizeof (out), NULL,
+				    font, HB_BUFFER_SERIALIZE_FORMAT_TEXT,
+				    HB_BUFFER_SERIALIZE_FLAG_DEFAULT);
+	fprintf (stderr, "Actual: %s\n", out);
+
+	hb_buffer_serialize_glyphs (ref_buffer, 0, hb_buffer_get_length (ref_buffer),
+				    out, sizeof (out), NULL,
+				    font, HB_BUFFER_SERIALIZE_FORMAT_TEXT,
+				    HB_BUFFER_SERIALIZE_FLAG_DEFAULT);
+	fprintf (stderr, "Expected: %s\n", out);
+
+	return 1;
+      }
+      hb_buffer_destroy (buffer);
+    }
+
+    hb_buffer_destroy (ref_buffer);
+  }
+
+  free (buffers);
+  free (threads);
+
+  hb_font_destroy (font);
+  hb_face_destroy (face);
+  hb_blob_destroy (blob);
+
+  return 0;
+}