diff --git a/lib/matplotlib/axes/_axes.py b/lib/matplotlib/axes/_axes.py
index 9037674780e2..9cff2a44d207 100644
--- a/lib/matplotlib/axes/_axes.py
+++ b/lib/matplotlib/axes/_axes.py
@@ -7629,6 +7629,8 @@ 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.specgram()
 
         if mode == 'complex':
             raise ValueError('Cannot plot a complex specgram')
diff --git a/lib/matplotlib/mlab.py b/lib/matplotlib/mlab.py
index e79d13f2a53e..d0255a9ca263 100644
--- a/lib/matplotlib/mlab.py
+++ b/lib/matplotlib/mlab.py
@@ -1113,6 +1113,8 @@ def specgram(x, NFFT=None, Fs=None, detrend=None, window=None,
         noverlap = 128  # default in _spectral_helper() is noverlap = 0
     if NFFT is None:
         NFFT = 256  # same default as in _spectral_helper()
+    if Fs is None:
+        Fs = 2 # same default as in _spectral_helper()
     if len(x) <= NFFT:
         cbook._warn_external("Only one segment is calculated since parameter "
                              "NFFT (=%d) >= signal length (=%d)." %