diff --git a/skimage/io/_plugins/matplotlib_plugin.py b/skimage/io/_plugins/matplotlib_plugin.py
index f578ecb9..652c8be1 100644
--- a/skimage/io/_plugins/matplotlib_plugin.py
+++ b/skimage/io/_plugins/matplotlib_plugin.py
@@ -2,6 +2,7 @@ import matplotlib.pyplot as plt
 
 def imshow(*args, **kwargs):
     kwargs.setdefault('interpolation', 'nearest')
+    kwargs.setdefault('cmap', 'gray')
     plt.imshow(*args, **kwargs)
 
 imread = plt.imread