matplotlib
diff --git a/‎lib/matplotlib/axes/_axes.py
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+2Lines changed: 2 additions & 0 deletions b/‎lib/matplotlib/axes/_axes.py
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+2Lines changed: 2 additions & 0 deletions
diff --git a/‎lib/matplotlib/tests/test_axes.py
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+7Lines changed: 7 additions & 0 deletions b/‎lib/matplotlib/tests/test_axes.py
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+7Lines changed: 7 additions & 0 deletions
@@ -7462,6 +7462,8 @@ def specgram(self, x, NFFT=None, Fs=None, Fc=None, detrend=None,
             Fc = 0  # same default as in mlab._spectral_helper()
         if noverlap is None:
             noverlap = 128  # same default as in mlab.specgram()
+        if Fs is None:
+            Fs = 2  # same default as in mlab._spectral_helper()
 
         if mode == 'complex':
             raise ValueError('Cannot plot a complex specgram')
 
@@ -4211,6 +4211,13 @@ def test_specgram_angle():
                                 scale="dB")
 
 
+def test_specgram_fs_none():
+    """Test axes.specgram when Fs is None, should not throw error."""
+    spec, freqs, t, im = plt.specgram(np.ones(300), Fs=None)
+    xmin, xmax, freq0, freq1 = im.get_extent()
+    assert xmin == 32 and xmax == 96
+
+
 @image_comparison(
     ["psd_freqs.png", "csd_freqs.png", "psd_noise.png", "csd_noise.png"],
     remove_text=True, tol=0.002)