Semantic-UI-Meteor: Unknown import: themes/default/globals/site.variables

I’m getting an unknown import error after running meteor update.

Changes to your project's package version selections from updating the release:

accounts-base           upgraded from 1.2.1 to 1.2.2
accounts-password       upgraded from 1.1.3 to 1.1.4
autoupdate              upgraded from 1.2.3 to 1.2.4
check                   upgraded from 1.0.6 to 1.1.0
coffeescript            upgraded from 1.0.10 to 1.0.11
ddp-common              upgraded from 1.2.1 to 1.2.2
ddp-server              upgraded from 1.2.1 to 1.2.2
ecmascript              upgraded from 0.1.5 to 0.1.6
ecmascript-collections  removed from your project
ecmascript-runtime      added, version 0.2.6
email                   upgraded from 1.0.7 to 1.0.8
es5-shim                upgraded from 4.1.13 to 4.1.14
less                    upgraded from 2.5.0_3 to 2.5.1
meteor                  upgraded from 1.1.9 to 1.1.10
mongo                   upgraded from 1.1.2 to 1.1.3
promise                 upgraded from 0.5.0 to 0.5.1
random                  upgraded from 1.0.4 to 1.0.5
reactive-dict           upgraded from 1.1.2 to 1.1.3
standard-minifiers      upgraded from 1.0.1 to 1.0.2
stylus                  upgraded from 2.511.0_2 to 2.511.1
templating              upgraded from 1.1.4 to 1.1.5
webapp                  upgraded from 1.2.2 to 1.2.3

myApp: updated to Meteor 1.2.1.

Changes to your project's package version selections from updating package versions:

alanning:roles            upgraded from 1.2.13 to 1.2.14
cosmos:browserify         upgraded from 0.8.0 to 0.8.1
ecwyne:mathjs             upgraded from 2.1.1 to 2.4.0
em0ney:amcharts           upgraded from 3.13.1_2 to 3.17.3
flemay:less-autoprefixer  upgraded from 1.1.0 to 1.2.0
jagi:astronomy            upgraded from 1.0.2 to 1.1.5
kadira:flow-router        upgraded from 2.6.2 to 2.7.0
kadira:react-layout       upgraded from 1.3.1 to 1.4.1
meteorhacks:kadira        upgraded from 2.24.0 to 2.24.1
semantic:ui               upgraded from 2.1.4 to 2.1.4_5
semantic:ui-data          upgraded from 2.1.4 to 2.1.4_5
u2622:persistent-session  upgraded from 0.4.3 to 0.4.4

=> Started proxy.
=> Started MongoDB.
=> Errors prevented startup:

   While processing files with flemay:less-autoprefixer (for target web.browser):
   client/lib/semantic-ui/theme.import.less:20: Unknown import: themes/default/globals/site.variables

=> Your application has errors. Waiting for file change.