Scan-build reports preprocessed files instead of source files

What can cause scan-build to report preprocessed files (like version.stdout.tcbuilder12.19259.UtL53O.ii ) instead of source files?

I have two environments - a dev machine and teamcity. On the dev machine I get reports as expected. On teamcity scan-build html reports are done for .ii files.

Is this configurable? Can I force source file reports in teamcity?