Hmm, this turned out to be caused by whitespace on earlier include lines. The following fixed it: - include /usr/share/cdbs/1/rules/debhelper.mk - include /usr/share/cdbs/1/class/python-distutils.mk - DEB_PYTHON_PRIVATE_MODULES_DIRS += /usr/share/arm +include /usr/share/cdbs/1/rules/debhelper.mk +include /usr/share/cdbs/1/class/python-distutils.mk +DEB_PYTHON_PRIVATE_MODULES_DIRS += /usr/share/arm