diff --git a/doc/api.rst b/doc/api.rst
index d4199fc1..e76e040b 100644
--- a/doc/api.rst
+++ b/doc/api.rst
@@ -430,7 +430,7 @@ Spectral
     :toctree: generated/
 
     plot_power_spectra
-    plot_spectra_3D
+    plot_spectra_3d
     plot_scv
     plot_scv_rs_lines
     plot_scv_rs_matrix
diff --git a/neurodsp/plts/__init__.py b/neurodsp/plts/__init__.py
index 4ce61552..5ce0b10d 100644
--- a/neurodsp/plts/__init__.py
+++ b/neurodsp/plts/__init__.py
@@ -4,7 +4,7 @@
                           plot_multi_time_series)
 from .filt import plot_filter_properties, plot_frequency_response, plot_impulse_response
 from .rhythm import plot_swm_pattern, plot_lagged_coherence
-from .spectral import (plot_power_spectra, plot_spectral_hist, plot_spectra_3D,
+from .spectral import (plot_power_spectra, plot_spectral_hist, plot_spectra_3d,
                        plot_scv, plot_scv_rs_lines, plot_scv_rs_matrix)
 from .timefrequency import plot_timefrequency
 from .aperiodic import plot_autocorr
diff --git a/neurodsp/plts/spectral.py b/neurodsp/plts/spectral.py
index 4e539b23..069c50fc 100644
--- a/neurodsp/plts/spectral.py
+++ b/neurodsp/plts/spectral.py
@@ -227,7 +227,7 @@ def plot_spectral_hist(freqs, power_bins, spectral_hist, spectrum_freqs=None,
 
 @savefig
 @style_plot
-def plot_spectra_3D(freqs, powers, log_freqs=False, log_powers=True, colors=None,
+def plot_spectra_3d(freqs, powers, log_freqs=False, log_powers=True, colors=None,
                     orientation=(20, -50), zoom=1.0, ax=None, **kwargs):
     """Plot a series of power spectra in a 3D plot.
 
diff --git a/neurodsp/tests/plts/test_spectral.py b/neurodsp/tests/plts/test_spectral.py
index 410b7f1f..fab0107c 100644
--- a/neurodsp/tests/plts/test_spectral.py
+++ b/neurodsp/tests/plts/test_spectral.py
@@ -70,16 +70,16 @@ def test_plot_spectral_hist(tsig_comb):
                        file_name='test_plot_spectral_hist.png')
 
 @plot_test
-def test_plot_spectra_3D(tsig_comb, tsig_burst):
+def test_plot_spectra_3d(tsig_comb, tsig_burst):
 
     freqs1, powers1 = compute_spectrum(tsig_comb, FS)
     freqs2, powers2 = compute_spectrum(tsig_burst, FS)
 
-    plot_spectra_3D([freqs1, freqs2], [powers1, powers2],
+    plot_spectra_3d([freqs1, freqs2], [powers1, powers2],
                     save_fig=True, file_path=TEST_PLOTS_PATH,
                     file_name='test_plot_spectral3D_1.png')
 
-    plot_spectra_3D(freqs1, [powers1, powers2, powers1, powers2],
+    plot_spectra_3d(freqs1, [powers1, powers2, powers1, powers2],
                     colors=['r', 'y', 'b', 'g'],
                     save_fig=True, file_path=TEST_PLOTS_PATH,
                     file_name='test_plot_spectral3D_2.png')