 <p>Unexpectedly, but I've found an answer.</p> <p>The only reason was in <a href="https://www.npmjs.org/package/source-map" rel="nofollow">source-map package</a>, which is in <code>brunch</code> dependencies. </p> <p>I've tried only two last versions of brunch: 1.7.13 and 1.7.14. Both of them requires <code>source-map</code> version <code>~0.1.26</code>. Which is for now resolved to <code>0.1.34</code> wherever you install brunch. </p> <p>And this is a root of evil.</p> <p><strong>What I've actually did is manual replace 0.1.34 with 0.1.33, directly in global <code>brunch/node_modules</code> folder.</strong></p> <p>And that's it. After this everything magically fixed, and my sourcemaps point to right lines again.</p> <p>Don't know WHY it is so - maybe, <code>source-map@0.1.34</code> is broken. But this really works.</p>