The en_US.aff and en_CA.aff dictionaries define their encoding as "SET UTF8" while hunspell expects "SET UTF-8". The other dictionaries in the package (en_AU, en_GB, en_ZA) use the correct syntax. Reproducible: Always Steps to Reproduce: echo "Hello world!" | LANG="en_US.utf-8" hunspell Actual Results: error: unknown encoding UTF8: using iso88591 as fallback error: unknown encoding UTF8: using iso88591 as fallback error: unknown encoding UTF8: using iso88591 as fallback error: unknown encoding UTF8: using iso88591 as fallback Hunspell 1.3.3 * * Expected Results: No errors. $ locale -a C de_DE de_DE@euro de_DE.iso88591 de_DE.iso885915@euro deutsch en_DK.utf8 en_US en_US.iso88591 en_US.utf8 german POSIX Changing the two affected .aff files to use "SET UTF-8" fixes the issue.
This should probably go upstream.
This should be an upstream bug. I will consider a patch to the dictionary files, if possible.
This is fixed in 20160201.