diff --git a/.github/workflows/linting.yml b/.github/workflows/linting.yml
index 065b05e..e9e619d 100644
--- a/.github/workflows/linting.yml
+++ b/.github/workflows/linting.yml
@@ -8,7 +8,7 @@ on:
 
 jobs:
   build:
-    runs-on: ubuntu-latest
+    runs-on: ubuntu-20.04
     steps:
     - uses: actions/checkout@v2
     - name: Set up Python
diff --git a/.github/workflows/packaging.yml b/.github/workflows/packaging.yml
index a6ae95c..355a389 100644
--- a/.github/workflows/packaging.yml
+++ b/.github/workflows/packaging.yml
@@ -6,7 +6,7 @@ on:
 
 jobs:
   deploy:
-    runs-on: ubuntu-latest
+    runs-on: ubuntu-20.04
     steps:
     - uses: actions/checkout@v2
     - name: Set up Python
diff --git a/.github/workflows/testing.yml b/.github/workflows/testing.yml
index fd121fb..df7ceee 100644
--- a/.github/workflows/testing.yml
+++ b/.github/workflows/testing.yml
@@ -10,7 +10,7 @@ jobs:
   build:
     strategy:
       matrix:
-        os: [ubuntu-latest, macos-latest, windows-latest]
+        os: [ubuntu-20.04, macos-latest, windows-latest]
         python-version: ['3.6', '3.7', '3.8']
     runs-on: ${{ matrix.os }}
     steps:
diff --git a/.gitignore b/.gitignore
index d2cad58..e524a23 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1,3 +1,8 @@
+# Working files
+*.mid
+*.midi
+# add any permanent files with git add -f
+
 # Byte-compiled / optimized / DLL files
 __pycache__/
 *.py[cod]
diff --git a/doc/source/read_write.rst b/doc/source/read_write.rst
index e31d3c0..91b6d38 100644
--- a/doc/source/read_write.rst
+++ b/doc/source/read_write.rst
@@ -20,4 +20,4 @@ Functions
     :noindex:
 
 .. note::
-    Writing the tempo array and downbeat array to tempo change and time signature change events are not supported yet.
+    Writing the downbeat array to time signature change events is not supported yet.
diff --git a/docs/_sources/read_write.rst.txt b/docs/_sources/read_write.rst.txt
index e31d3c0..91b6d38 100644
--- a/docs/_sources/read_write.rst.txt
+++ b/docs/_sources/read_write.rst.txt
@@ -20,4 +20,4 @@ Functions
     :noindex:
 
 .. note::
-    Writing the tempo array and downbeat array to tempo change and time signature change events are not supported yet.
+    Writing the downbeat array to time signature change events is not supported yet.
diff --git a/docs/doc.html b/docs/doc.html
index 30b7afe..12acb47 100644
--- a/docs/doc.html
+++ b/docs/doc.html
@@ -10,7 +10,7 @@
   <!--[if lt IE 9]>
     <script src="_static/js/html5shiv.min.js"></script>
   <![endif]-->
-  
+
         <script data-url_root="./" id="documentation_options" src="_static/documentation_options.js"></script>
         <script src="_static/jquery.js"></script>
         <script src="_static/underscore.js"></script>
@@ -19,10 +19,10 @@
     <script src="_static/js/theme.js"></script>
     <link rel="index" title="Index" href="genindex.html" />
     <link rel="search" title="Search" href="search.html" />
-    <link rel="prev" title="Metrics" href="metrics.html" /> 
+    <link rel="prev" title="Metrics" href="metrics.html" />
 </head>
 
-<body class="wy-body-for-nav"> 
+<body class="wy-body-for-nav">
   <div class="wy-grid-for-nav">
     <nav data-toggle="wy-nav-shift" class="wy-nav-side">
       <div class="wy-side-scroll">
@@ -71,7 +71,7 @@
 </div>
           <div role="main" class="document" itemscope="itemscope" itemtype="http://schema.org/Article">
            <div itemprop="articleBody">
-             
+
   <section id="module-pypianoroll">
 <span id="technical-documentation"></span><h1>Technical Documentation<a class="headerlink" href="#module-pypianoroll" title="Permalink to this headline"></a></h1>
 <p>A Python library for handling multitrack pianorolls.</p>
@@ -1797,8 +1797,7 @@ <h2>Features<a class="headerlink" href="#features" title="Permalink to this head
 <dl class="field-list simple">
 <dt class="field-odd">Parameters</dt>
 <dd class="field-odd"><ul class="simple">
-<li><p><strong>default_tempo</strong> (int, default: <cite>pypianoroll.DEFAULT_TEMPO</cite> (120)) – Default tempo to use. If attribute <cite>tempo</cite> is available, use its
-first element.</p></li>
+<li><p><strong>default_tempo</strong> (int, default: <cite>pypianoroll.DEFAULT_TEMPO</cite> (120)) – Default tempo to use. If attribute <cite>tempo</cite> is available, encorporate it into the midi file with any tempo changes and time signature changes that occur.</p></li>
 <li><p><strong>default_velocity</strong> (int, default: <cite>pypianoroll.DEFAULT_VELOCITY</cite> (64)) – Default velocity to assign to binarized tracks.</p></li>
 </ul>
 </dd>
@@ -1811,8 +1810,7 @@ <h2>Features<a class="headerlink" href="#features" title="Permalink to this head
 </dl>
 <p class="rubric">Notes</p>
 <ul class="simple">
-<li><p>Tempo changes are not supported.</p></li>
-<li><p>Time signature changes are not supported.</p></li>
+<li><p>Time signature changes default to */4.</p></li>
 <li><p>The velocities of the converted piano rolls will be clipped to
 [0, 127].</p></li>
 <li><p>Adjacent nonzero values of the same pitch will be considered
@@ -1928,7 +1926,7 @@ <h2>Features<a class="headerlink" href="#features" title="Permalink to this head
   Built with <a href="https://www.sphinx-doc.org/">Sphinx</a> using a
     <a href="https://github.com/readthedocs/sphinx_rtd_theme">theme</a>
     provided by <a href="https://readthedocs.org">Read the Docs</a>.
-   
+
 
 </footer>
         </div>
@@ -1939,7 +1937,7 @@ <h2>Features<a class="headerlink" href="#features" title="Permalink to this head
       jQuery(function () {
           SphinxRtdTheme.Navigation.enable(true);
       });
-  </script> 
+  </script>
 
 </body>
-</html>
\ No newline at end of file
+</html>
diff --git a/docs/read_write.html b/docs/read_write.html
index 8540b6d..7b994a4 100644
--- a/docs/read_write.html
+++ b/docs/read_write.html
@@ -10,7 +10,7 @@
   <!--[if lt IE 9]>
     <script src="_static/js/html5shiv.min.js"></script>
   <![endif]-->
-  
+
         <script data-url_root="./" id="documentation_options" src="_static/documentation_options.js"></script>
         <script src="_static/jquery.js"></script>
         <script src="_static/underscore.js"></script>
@@ -19,10 +19,10 @@
     <link rel="index" title="Index" href="genindex.html" />
     <link rel="search" title="Search" href="search.html" />
     <link rel="next" title="Visualization" href="visualization.html" />
-    <link rel="prev" title="Save &amp; Load" href="save_load.html" /> 
+    <link rel="prev" title="Save &amp; Load" href="save_load.html" />
 </head>
 
-<body class="wy-body-for-nav"> 
+<body class="wy-body-for-nav">
   <div class="wy-grid-for-nav">
     <nav data-toggle="wy-nav-shift" class="wy-nav-side">
       <div class="wy-side-scroll">
@@ -71,7 +71,7 @@
 </div>
           <div role="main" class="document" itemscope="itemscope" itemtype="http://schema.org/Article">
            <div itemprop="articleBody">
-             
+
   <section id="read-write">
 <h1>Read &amp; Write<a class="headerlink" href="#read-write" title="Permalink to this headline"></a></h1>
 <p>Pypianoroll currently supports reading from and writing to MIDI files.</p>
@@ -178,8 +178,7 @@ <h2>Functions<a class="headerlink" href="#functions" title="Permalink to this he
 <dl class="field-list simple">
 <dt class="field-odd">Parameters</dt>
 <dd class="field-odd"><ul class="simple">
-<li><p><strong>default_tempo</strong> (int, default: <cite>pypianoroll.DEFAULT_TEMPO</cite> (120)) – Default tempo to use. If attribute <cite>tempo</cite> is available, use its
-first element.</p></li>
+<li><p><strong>default_tempo</strong> (int, default: <cite>pypianoroll.DEFAULT_TEMPO</cite> (120)) – Default tempo to use. If attribute <cite>tempo</cite> is available, encorporate it into the midi file with any tempo changes and time signature changes that occur.</p></li>
 <li><p><strong>default_velocity</strong> (int, default: <cite>pypianoroll.DEFAULT_VELOCITY</cite> (64)) – Default velocity to assign to binarized tracks.</p></li>
 </ul>
 </dd>
@@ -192,8 +191,7 @@ <h2>Functions<a class="headerlink" href="#functions" title="Permalink to this he
 </dl>
 <p class="rubric">Notes</p>
 <ul class="simple">
-<li><p>Tempo changes are not supported.</p></li>
-<li><p>Time signature changes are not supported.</p></li>
+<li><p>Time signature changes default to */4.</p></li>
 <li><p>The velocities of the converted piano rolls will be clipped to
 [0, 127].</p></li>
 <li><p>Adjacent nonzero values of the same pitch will be considered
@@ -203,7 +201,7 @@ <h2>Functions<a class="headerlink" href="#functions" title="Permalink to this he
 
 <div class="admonition note">
 <p class="admonition-title">Note</p>
-<p>Writing the tempo array and downbeat array to tempo change and time signature change events are not supported yet.</p>
+<p>Writing the downbeat array to time signature change events is not supported yet.</p>
 </div>
 </section>
 </section>
@@ -225,7 +223,7 @@ <h2>Functions<a class="headerlink" href="#functions" title="Permalink to this he
   Built with <a href="https://www.sphinx-doc.org/">Sphinx</a> using a
     <a href="https://github.com/readthedocs/sphinx_rtd_theme">theme</a>
     provided by <a href="https://readthedocs.org">Read the Docs</a>.
-   
+
 
 </footer>
         </div>
@@ -236,7 +234,7 @@ <h2>Functions<a class="headerlink" href="#functions" title="Permalink to this he
       jQuery(function () {
           SphinxRtdTheme.Navigation.enable(true);
       });
-  </script> 
+  </script>
 
 </body>
-</html>
\ No newline at end of file
+</html>
diff --git a/pypianoroll/inputs.py b/pypianoroll/inputs.py
index 9f79205..2d066d9 100644
--- a/pypianoroll/inputs.py
+++ b/pypianoroll/inputs.py
@@ -205,7 +205,7 @@ def from_pretty_midi(
 
     # Parse downbeat array
     if not midi.time_signature_changes:
-        # This probably won't happen as pretty_midi always add a 4/4 time
+        # This probably won't happen as pretty_midi always adds a 4/4 time
         # signature at time 0
         beat = None
         downbeat = None
@@ -234,7 +234,7 @@ def from_pretty_midi(
     one_more_beat = 2 * beat_times[-1] - beat_times[-2]
     beat_times_one_more = np.append(beat_times, one_more_beat)
     bpm = 60.0 / np.diff(beat_times_one_more)
-    tempo = np.tile(bpm, (1, 24)).reshape(-1, 1)
+    tempo = np.repeat(bpm, resolution).reshape(-1, 1)
 
     # Parse the tracks
     tracks = []
diff --git a/pypianoroll/metrics.py b/pypianoroll/metrics.py
index 489b6d6..a6b6b3f 100644
--- a/pypianoroll/metrics.py
+++ b/pypianoroll/metrics.py
@@ -188,7 +188,7 @@ def qualified_note_rate(pianoroll: ndarray, threshold: float = 2) -> float:
        2018.
 
     """
-    if np.issubdtype(pianoroll.dtype, np.bool_):
+    if np.issubdtype(pianoroll.dtype, bool):
         pianoroll = pianoroll.astype(np.uint8)
     padded = np.pad(pianoroll, ((1, 1), (0, 0)), "constant")
     diff = np.diff(padded, axis=0).reshape(-1)
diff --git a/pypianoroll/multitrack.py b/pypianoroll/multitrack.py
index 2e52ac7..2f3e7f5 100644
--- a/pypianoroll/multitrack.py
+++ b/pypianoroll/multitrack.py
@@ -11,7 +11,7 @@
 - DEFAULT_RESOLUTION
 
 """
-from typing import List, Sequence, TypeVar
+from typing import List, Sequence, TypeVar, Union
 
 import numpy as np
 from matplotlib.axes import Axes
@@ -66,7 +66,8 @@ class Multitrack:
         Time steps per quarter note.
     tempo : ndarray, dtype=float, shape=(?, 1), optional
         Tempo (in qpm) at each time step. Length is the total number
-        of time steps. Cast to float if not of float type.
+        of time steps. Cast to float if not of float type. Alternatively,
+        enter a single float or integer and the array will be generated.
     beat : ndarray, dtype=bool, shape=(?, 1), optional
         A boolean array that indicates whether the time step contains a
         beat. Length is the total number of time steps. Cast to bool if
@@ -84,7 +85,7 @@ def __init__(
         self,
         name: str = None,
         resolution: int = None,
-        tempo: ndarray = None,
+        tempo: Union[ndarray, int, float] = None,
         beat: ndarray = None,
         downbeat: ndarray = None,
         tracks: Sequence[Track] = None,
@@ -96,8 +97,17 @@ def __init__(
         else:
             self.resolution = DEFAULT_RESOLUTION
 
+        if tracks is None:
+            self.tracks = []
+        elif isinstance(tracks, list):
+            self.tracks = tracks
+        else:
+            self.tracks = list(tracks)
+
         if tempo is None:
             self.tempo = None
+        elif isinstance(tempo, int) or isinstance(tempo, float):
+            self.tempo = np.tile(tempo, (self.get_max_length(), 1)).astype(float)
         elif np.issubdtype(tempo.dtype, np.floating):
             self.tempo = tempo
         else:
@@ -117,13 +127,6 @@ def __init__(
         else:
             self.downbeat = np.asarray(downbeat).astype(bool)
 
-        if tracks is None:
-            self.tracks = []
-        elif isinstance(tracks, list):
-            self.tracks = tracks
-        else:
-            self.tracks = list(tracks)
-
     def __len__(self) -> int:
         return len(self.tracks)
 
@@ -187,7 +190,7 @@ def _validate_type(self, attr):
         elif attr == "beat":
             if not isinstance(self.beat, np.ndarray):
                 raise TypeError("`beat` must be a NumPy array.")
-            if not np.issubdtype(self.beat.dtype, np.bool_):
+            if not np.issubdtype(self.beat.dtype, bool):
                 raise TypeError(
                     "`beat` must be of data type bool, but got data type"
                     f"{self.beat.dtype}."
@@ -195,7 +198,7 @@ def _validate_type(self, attr):
         elif attr == "downbeat":
             if not isinstance(self.downbeat, np.ndarray):
                 raise TypeError("`downbeat` must be a NumPy array.")
-            if not np.issubdtype(self.downbeat.dtype, np.bool_):
+            if not np.issubdtype(self.downbeat.dtype, bool):
                 raise TypeError(
                     "`downbeat` must be of data type bool, but got data type"
                     f"{self.downbeat.dtype}."
@@ -248,16 +251,16 @@ def _validate(self, attr):
             if self.resolution < 1:
                 raise ValueError("`resolution` must be a positive integer.")
         elif attr == "tempo":
-            if self.tempo.ndim != 1:
-                raise ValueError("`tempo` must be a 1D NumPy array.")
+            if self.tempo.ndim != 2:
+                raise ValueError("`tempo` must be a 2D NumPy array of shape (?,1)")
             if np.any(self.tempo <= 0.0):
                 raise ValueError("`tempo` must contain only positive numbers.")
         elif attr == "beat":
             if self.beat.ndim != 1:
                 raise ValueError("`beat` must be a 1D NumPy array.")
         elif attr == "downbeat":
-            if self.downbeat.ndim != 1:
-                raise ValueError("`downbeat` must be a 1D NumPy array.")
+            if self.downbeat.ndim != 2 or self.downbeat.shape[1] != 1:
+                raise ValueError("`downbeat` must be a 2D NumPy array of shape (?,1).")
         elif attr == "tracks":
             for track in self.tracks:
                 track.validate()
diff --git a/pypianoroll/outputs.py b/pypianoroll/outputs.py
index b1ee31d..b06032b 100644
--- a/pypianoroll/outputs.py
+++ b/pypianoroll/outputs.py
@@ -16,6 +16,7 @@
 """
 import json
 import zipfile
+from fractions import Fraction
 from copy import deepcopy
 from operator import attrgetter
 from pathlib import Path
@@ -23,7 +24,6 @@
 
 import numpy as np
 import pretty_midi
-import scipy.stats
 from pretty_midi import Instrument, PrettyMIDI
 
 from .track import BinaryTrack, StandardTrack
@@ -114,8 +114,8 @@ def to_pretty_midi(
     Parameters
     ----------
     default_tempo : int, default: `pypianoroll.DEFAULT_TEMPO` (120)
-        Default tempo to use. If attribute `tempo` is available, use its
-        first element.
+        Default tempo to use. If attribute `tempo` is available, encorporate
+        it into the midi file with any tempo changes and time signature changes that occur
     default_velocity : int, default: `pypianoroll.DEFAULT_VELOCITY` (64)
         Default velocity to assign to binarized tracks.
 
@@ -126,8 +126,7 @@ def to_pretty_midi(
 
     Notes
     -----
-    - Tempo changes are not supported.
-    - Time signature changes are not supported.
+    - Time signature changes default to */4.
     - The velocities of the converted piano rolls will be clipped to
       [0, 127].
     - Adjacent nonzero values of the same pitch will be considered
@@ -135,17 +134,41 @@ def to_pretty_midi(
 
     """
     if default_tempo is not None:
-        tempo = default_tempo
+        tempo = np.full(multitrack.get_max_length(), default_tempo)
     elif multitrack.tempo is not None:
-        tempo = float(scipy.stats.hmean(multitrack.tempo))
+        tempo = multitrack.tempo[:,0]
     else:
-        tempo = DEFAULT_TEMPO
+        tempo = np.full(multitrack.get_max_length(), DEFAULT_TEMPO)
 
     # Create a PrettyMIDI instance
-    midi = PrettyMIDI(initial_tempo=tempo)
+    midi = PrettyMIDI(initial_tempo=tempo[0])
 
     # Compute length of a time step
     time_step_length = 60.0 / tempo / multitrack.resolution
+    # Use prefix sum for fast computation of elapsed time
+    prefix = np.concatenate(((0,), np.add.accumulate(time_step_length)))
+
+    # Find tempi changes
+    tempi_changes = np.diff(tempo).nonzero()[0] + 1
+
+    # Copied from pretty-midi source code (https://github.com/craffel/pretty-midi/blob/241279b91196125881724e53ea436e1b9181f74b/pretty_midi/pretty_midi.py)
+    # Changes tempo by updating ticks
+    last_tick, last_tick_scale = midi._tick_scales[0]
+    previous_time = 0.
+    for time, tempo in zip(prefix[tempi_changes], tempo[tempi_changes]):
+        # Compute new tick location as the last tick plus the time between
+        # the last and next tempo change, scaled by the tick scaling
+        tick = last_tick + (time - previous_time)/last_tick_scale
+        # Update the tick scale
+        tick_scale = 60.0/(tempo*midi.resolution)
+        # Don't add tick scales if they are repeats
+        if tick_scale != last_tick_scale:
+            # Add in the new tick scale
+            midi._tick_scales.append((int(round(tick)), tick_scale))
+            # Update the time and values of the previous tick scale
+            previous_time = time
+            last_tick, last_tick_scale = tick, tick_scale
+    midi._update_tick_to_time(midi._tick_scales[-1][0] + 1)
 
     for track in multitrack.tracks:
         instrument = Instrument(
@@ -168,9 +191,9 @@ def to_pretty_midi(
         positives = np.nonzero((diff > 0).T)
         pitches = positives[0]
         note_ons = positives[1]
-        note_on_times = time_step_length * note_ons
+        note_on_times = prefix[note_ons]
         note_offs = np.nonzero((diff < 0).T)[1]
-        note_off_times = time_step_length * note_offs
+        note_off_times = prefix[note_offs]
 
         for idx, pitch in enumerate(pitches):
             velocity = np.mean(clipped[note_ons[idx] : note_offs[idx], pitch])
@@ -185,6 +208,22 @@ def to_pretty_midi(
         instrument.notes.sort(key=attrgetter("start"))
         midi.instruments.append(instrument)
 
+    if multitrack.downbeat is not None:
+        # Find downbeat positions
+        downbeats = np.concatenate((multitrack.downbeat[:,0], (True,)))
+        indices = np.where(downbeats)[0]
+
+        for i in range(len(indices) - 1):
+            # Calculate number of beats
+            beats = Fraction((indices[i+1] - indices[i]) / multitrack.resolution / 4).limit_denominator(16)
+            time = prefix[indices[i]] if i != 0 else 0 # include timesignature at time 0
+            # Find the first denominator that fits into the beat without 1/*
+            beat_denominators = [4, 8, 16]
+            for denominator in beat_denominators:
+                if denominator % beats.denominator == 0 and (denominator == beat_denominators[-1] or beats.numerator * denominator // beats.denominator != 1):
+                    midi.time_signature_changes.append(pretty_midi.TimeSignature(beats.numerator * denominator // beats.denominator, denominator, time))
+                    break
+
     return midi
 
 
diff --git a/setup.py b/setup.py
index e2d7a75..6c1afd4 100644
--- a/setup.py
+++ b/setup.py
@@ -40,7 +40,7 @@ def _get_version():
         include=["pypianoroll", "pypianoroll.*"], exclude=["tests"]
     ),
     install_requires=[
-        "numpy>=1.12.0",
+        "numpy>=1.12.0,<1.24",
         "scipy>=1.0.0",
         "pretty_midi>=0.2.8",
         "matplotlib>=1.5",
diff --git a/tests/test_multitrack.py b/tests/test_multitrack.py
index 33a2aa7..6e665da 100644
--- a/tests/test_multitrack.py
+++ b/tests/test_multitrack.py
@@ -8,10 +8,12 @@
 
 
 def test_repr(multitrack):
+    # print(repr(multitrack))
     assert repr(multitrack) == (
         "Multitrack(name='test', resolution=24, "
+        "tempo=array(shape=(96, 1), dtype=float64), "
         "beat=array(shape=(96,), dtype=bool), "
-        "downbeat=array(shape=(96,), dtype=bool), tracks=["
+        "downbeat=array(shape=(96, 1), dtype=bool), tracks=["
         "StandardTrack(name='track_1', program=0, is_drum=False, "
         "pianoroll=array(shape=(96, 128), dtype=uint8)), "
         "BinaryTrack(name='track_2', program=0, is_drum=True, "
@@ -45,6 +47,10 @@ def test_get_downbeat_steps(multitrack):
     assert np.all(multitrack.get_downbeat_steps() == [0])
 
 
+def test_tempo(multitrack):
+    assert multitrack.tempo.shape == (96, 1)
+    assert np.allclose(multitrack.tempo, 120)
+
 def test_set_nonzeros(multitrack):
     multitrack.set_nonzeros(50)
     assert isinstance(multitrack.tracks[1], StandardTrack)
@@ -93,8 +99,8 @@ def multitrack_to_blend():
     track_2 = StandardTrack(
         name="track_2", program=0, is_drum=True, pianoroll=pianoroll_2
     )
-    downbeat = np.zeros((96,), bool)
-    downbeat[0] = True
+    downbeat = np.zeros((96, 1), bool)
+    downbeat[0,0] = True
     return Multitrack(
         name="test",
         resolution=24,
@@ -125,7 +131,7 @@ def test_blend_max(multitrack_to_blend):
 
 
 def test_append(multitrack):
-    pianoroll = np.zeros((96, 128), np.bool_)
+    pianoroll = np.zeros((96, 128), bool)
     pianoroll[:95:16, 41] = True
     track_to_append = BinaryTrack(name="track_3", pianoroll=pianoroll)
     multitrack.append(track_to_append)
@@ -150,13 +156,13 @@ def test_pad_to_same(multitrack):
     track_1 = StandardTrack(
         name="track_1", program=0, is_drum=False, pianoroll=pianoroll_1
     )
-    pianoroll_2 = np.zeros((96, 128), np.bool)
+    pianoroll_2 = np.zeros((96, 128), bool)
     pianoroll_2[0:95:16, 36] = True
     track_2 = BinaryTrack(
         name="track_2", program=0, is_drum=True, pianoroll=pianoroll_2
     )
-    downbeat = np.zeros((96,), bool)
-    downbeat[0] = True
+    downbeat = np.zeros((96, 1), bool)
+    downbeat[0,0] = True
     multitrack = Multitrack(
         name="test",
         resolution=24,
@@ -174,12 +180,12 @@ def test_remove_empty():
     track_1 = StandardTrack(
         name="track_1", program=0, is_drum=False, pianoroll=pianoroll_1
     )
-    pianoroll_2 = np.zeros((96, 128), np.bool)
+    pianoroll_2 = np.zeros((96, 128), bool)
     track_2 = StandardTrack(
         name="track_2", program=0, is_drum=True, pianoroll=pianoroll_2
     )
-    downbeat = np.zeros((96,), bool)
-    downbeat[0] = True
+    downbeat = np.zeros((96, 1), bool)
+    downbeat[0,0] = True
     multitrack = Multitrack(
         name="test",
         resolution=24,
diff --git a/tests/utils.py b/tests/utils.py
index 0300628..3aa6a3f 100644
--- a/tests/utils.py
+++ b/tests/utils.py
@@ -12,19 +12,20 @@ def multitrack():
     track_1 = StandardTrack(
         name="track_1", program=0, is_drum=False, pianoroll=pianoroll_1
     )
-    pianoroll_2 = np.zeros((96, 128), np.bool)
+    pianoroll_2 = np.zeros((96, 128), bool)
     pianoroll_2[:95:16, 36] = True
     track_2 = BinaryTrack(
         name="track_2", program=0, is_drum=True, pianoroll=pianoroll_2
     )
     beat = np.zeros((96,), bool)
     beat[:96:24] = True
-    downbeat = np.zeros((96,), bool)
-    downbeat[0] = True
+    downbeat = np.zeros((96,1), bool)
+    downbeat[0,0] = True
     return Multitrack(
         name="test",
         resolution=24,
         beat=beat,
         downbeat=downbeat,
         tracks=[track_1, track_2],
+        tempo=120
     )
