Commands in acronym text - makeglossaries errors

I have the following acronyms defined:

%% ACRONYM CONFIG
usepackage[xindy,nonumberlist,nomain,acronym,nopostdot,toc=false]{glossaries}
renewcommand*{glsclearpage}{} % remove the unwanted blank page
usepackage{glossary-mcols} % two column
renewcommand*{glspostdescription}{} % no dots
makeglossaries
glsaddall

newacronym{I2C}{Itextsuperscript{2}C}{Inter-Integrated Circuit}
newacronym{I2S}{Itextsuperscript{2}S}{Inter-IC Sound}

makeglossaries thesis prints the following error:

WARNING: Would replace complete index key by empty string, ignoring
     #<ordrule-regexp: '[a-zA-Z@]+ *' => '' :again NIL :only-at-start NIL>
**Warning:**

Sort key required for entries only containing command names.
Attempting to determine which entries have problem sort keys.
Parsing 'thesis.acn'
2 problematic entries found:

Label: 'I2C'. Sort value : 'I2C'
(Try adding sort={I2C} to the definition.)
Label: 'I2S'. Sort value : 'I2S'
(Try adding sort={I2S} to the definition.)

The sort={I2S} piece looks like what you would use in a glossary entry, but I have acronyms. Where do I put it?

I tried the following, but it didn’t do anything:

newacronym[sort={I2C}]{I2C}{Itextsuperscript{2}C}{Inter-Integrated Circuit}
newacronym[sort={I2S}]{I2S}{Itextsuperscript{2}S}{Inter-IC Sound}

newacronym[sort={I2C}]{I2C}{Itextsuperscript{2}C}{Inter-Integrated Circuit}
newacronym[sort={I2S}]{I2S}{Itextsuperscript{2}S}{Inter-IC Sound}