"invalid value" error if 'line-height' declaration does not end with semicolon

An "invalid value" error is reported when a 'line-height' 
declaration does not end with a semicolon, like:

.test {
   line-height: 2
}

If I terminate the declaration with a semicolon, no error is reported:

.test {
   line-height: 2;
}

I haven't observed such error reported for other property 
declarations, like:

.test {
   margin: 0
}

As far as I'm aware declaration as the first one is o.k. and there 
should be no error.

-- 
Stanimir