Using Flycheck, I get a green thin jagged underline line for style-guide violations, and a red thin jagged underline for syntax errors (see below).

Is it possible to change the thickness or the color of the line? Namely, I'd like the red to be more noticeable upon my grey background. I would prefer if it was light red / pink instead.

1 Answer 1


You can change the color but you cannot change the thickness.

There are two ways:

  1. M-xlist-faces-displayRET, find flycheck-error click it, edit the underline color -> Apply and Save

  2. You can add some piece of code to your init file:

    (set-face-attribute 'flycheck-error nil :underline '(:color "red2" :style wave)) where red2 is the color used.

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