diff --git a/docs/pyerrors/fits.html b/docs/pyerrors/fits.html
index 0df35391..ac96d992 100644
--- a/docs/pyerrors/fits.html
+++ b/docs/pyerrors/fits.html
@@ -662,7 +662,7 @@
554 for key in key_ls:
555 if not callable(funcd[key]):
556 raise TypeError('func (key=' + key + ') is not a function.')
-557 if len(xd[key]) != len(yd[key]):
+557 if np.asarray(xd[key]).shape[-1] != len(yd[key]):
558 raise Exception('x and y input (key=' + key + ') do not have the same length')
559 for i in range(100):
560 try: