I'm getting this (with 'sh validate -legacy'). Oddly * It does not happen on HEAD * It does happen on wip/T19495, a tiny patch with one innocuous change to GHC.Tc.Gen.HsType I can't see how my patch could possible cause "missing files" in ghc-bignum! I'm guessing that there is a missing dependency that someone doesn't show up in master, but does in my branch, randomly. There's something funny about ghc-bignum; it doesn't seem to be a regular library Can anyone help? Thanks Simon "inplace/bin/ghc-stage1" -hisuf hi -osuf o -hcsuf hc -static -O -H64m -Wall -fllvm-fill-undef-with-garbage -Werror -this-unit-id base-4.16.0.0 -hide-all-packages -package-env - -i -ilibraries/base/. -ilibraries/base/dist-install/build -Ilibraries/base/dist-install/build -ilibraries/base/dist-install/build/./autogen -Ilibraries/base/dist-install/build/./autogen -Ilibraries/base/include -Ilibraries/base/dist-install/build/include -optP-include -optPlibraries/base/dist-install/build/./autogen/cabal_macros.h -package-id ghc-bignum-1.0 -package-id ghc-prim-0.8.0 -package-id rts -this-unit-id base -Wcompat -Wnoncanonical-monad-instances -XHaskell2010 -O -dcore-lint -ticky -Wwarn -no-user-package-db -rtsopts -Wno-trustworthy-safe -Wno-deprecated-flags -Wnoncanonical-monad-instances -outputdir libraries/base/dist-install/build -dynamic-too -c libraries/base/./GHC/Exception/Type.hs-boot -o libraries/base/dist-install/build/GHC/Exception/Type.o-boot -dyno libraries/base/dist-install/build/GHC/Exception/Type.dyn_o-boot Failed to load interface for 'GHC.Num.Integer' There are files missing in the 'ghc-bignum' package, try running 'ghc-pkg check'. Use -v (or `:set -v` in ghci) to see a list of the files searched for. make[1]: *** [libraries/base/ghc.mk:4: libraries/base/dist-install/build/GHC/Exception/Type.o-boot] Error 1 make[1]: *** Waiting for unfinished jobs....