unique filter broken with multi-word parameters?

Hello, I have JSON data that includes multi-word parameters. When I try the unique filter in my ng-repeat I get the error that the second word in the parameter is an unexpected token.

Does the unique filter support multi-word keys/parameters? I've tried wrapping in single quotes, double curly braces to no avail.

(in the following, histConfig.column is a scope variable referring to a multi-word key in importedData)
ng-repeat="row in importedData | uniq:histConfig.column"

error msg:
Error: [$parse:syntax] Syntax Error: Token 'Provider' is an unexpected token at column 11 of the expression [Referring Provider] starting at [Provider].