The clamav package can't be built right know because it depends on llvm-3.6 which fails to build. In fact, all the llvm-3.* packages fail to build with the same error: --8<---------------cut here---------------start------------->8--- The following derivation will be built: /gnu/store/7rh78xkkglsx289s9j6fdxwfwakqdhv8-llvm-3.6.2.drv building /gnu/store/7rh78xkkglsx289s9j6fdxwfwakqdhv8-llvm-3.6.2.drv... ice-9/read.scm:126:4: In procedure read-expr*: /gnu/store/kj78hgwyb11z2sxz4xfd3v9sd93xk7yc-llvm-3.6.2-builder:1:3078: Unknown # object: "#<" builder for `/gnu/store/7rh78xkkglsx289s9j6fdxwfwakqdhv8-llvm-3.6.2.drv' failed with exit code 1 build of /gnu/store/7rh78xkkglsx289s9j6fdxwfwakqdhv8-llvm-3.6.2.drv failed View build log at '/var/log/guix/drvs/7r/h78xkkglsx289s9j6fdxwfwakqdhv8-llvm-3.6.2.drv.gz'. guix build: error: build of `/gnu/store/7rh78xkkglsx289s9j6fdxwfwakqdhv8-llvm-3.6.2.drv' failed --8<---------------cut here---------------end--------------->8--- It looks like the problem comes from a gexp in the builder. There's a gexp inside another gexp, but I don't know if that's the problem: --8<---------------cut here---------------start------------->8--- #:phases (modify-phases #8--- The full builder file is in attachment.