diff --git a/src/meson.build b/src/meson.build
index 00132b011..8e40e0498 100644
--- a/src/meson.build
+++ b/src/meson.build
@@ -726,6 +726,7 @@ if get_option('tests').enabled()
     'test-bimap': ['test-bimap.cc', 'hb-static.cc'],
     'test-cff': ['test-cff.cc', 'hb-static.cc'],
     'test-classdef-graph': ['graph/test-classdef-graph.cc', 'hb-static.cc', 'graph/gsubgpos-context.cc'],
+    'test-decycler': ['test-decycler.cc', 'hb-static.cc'],
     'test-iter': ['test-iter.cc', 'hb-static.cc'],
     'test-machinery': ['test-machinery.cc', 'hb-static.cc'],
     'test-map': ['test-map.cc', 'hb-static.cc'],
diff --git a/src/test-decycler.cc b/src/test-decycler.cc
new file mode 100644
index 000000000..b6fa0f747
--- /dev/null
+++ b/src/test-decycler.cc
@@ -0,0 +1,88 @@
+/*
+ * Copyright © 2025 Behdad Esfahbod
+ *
+ *  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.
+ *
+ * Author(s): Behdad Esfahbod
+ */
+
+#include "hb.hh"
+#include "hb-decycler.hh"
+
+static void
+tree_recurse (unsigned value,
+	      unsigned max_value,
+	      hb_decycler_t &decycler)
+{
+  if (value >= max_value)
+		return;
+
+  hb_decycler_node_t node (decycler);
+
+  bool ret = node.visit (value);
+  assert (ret);
+
+  tree_recurse (value * 2 + 1, max_value, decycler);
+  tree_recurse (value * 2 + 2, max_value, decycler);
+}
+
+static void
+test_tree ()
+{
+  hb_decycler_t decycler;
+  tree_recurse (0, 64, decycler);
+}
+
+static void
+cycle_recurse (signed value,
+	       signed cycle_length,
+	       hb_decycler_t &decycler)
+{
+  assert (cycle_length > 0);
+
+  hb_decycler_node_t node (decycler);
+
+  if (!node.visit (value))
+    return;
+
+  if (value >= cycle_length)
+    value = value % cycle_length;
+
+  cycle_recurse (value + 1, cycle_length, decycler);
+}
+
+static void
+test_cycle ()
+{
+  hb_decycler_t decycler;
+  cycle_recurse (2, 3, decycler);
+  cycle_recurse (-20, 8, decycler);
+}
+
+int
+main (int argc, char **argv)
+{
+  test_tree ();
+  test_cycle ();
+
+  return 0;
+}
+