diff --git a/.travis.yml b/.travis.yml
index a1e744f..782df42 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -93,24 +93,26 @@ script:
   - cd ${DISTDIR} || false
   - find . -maxdepth 1 -name '*.tar.gz' -exec tar -xvf '{}' \;
   - "printf 'packages: xmonad-*/*.cabal\\n' > cabal.project"
-  - cat cabal.project
+  - touch cabal.project.local
+  - "if ! $NOINSTALLEDCONSTRAINTS; then for pkg in $($HCPKG list --simple-output); do echo $pkg  | grep -vw -- xmonad | sed 's/^/constraints: /' | sed 's/-[^-]*$/ installed/' >> cabal.project.local; done; fi"
+  - cat cabal.project || true
+  - cat cabal.project.local || true
   # this builds all libraries and executables (without tests/benchmarks)
   - cabal new-build -w ${HC} --disable-tests --disable-benchmarks all
 
-  # Build with installed constraints for packages in global-db
-  - if $INSTALLED; then echo cabal new-build -w ${HC} --disable-tests --disable-benchmarks $(${HCPKG} list --global --simple-output --names-only | sed 's/\([a-zA-Z0-9-]\{1,\}\) */--constraint="\1 installed" /g') all | sh; else echo "Not building with installed constraints"; fi
-
   # build & run tests, build benchmarks
   - cabal new-build -w ${HC} ${TEST} ${BENCH} all
   - if [ "x$TEST" = "x--enable-tests" ]; then cabal new-test -w ${HC} ${TEST} ${BENCH} all; fi
 
-  # We don't do cabal check because it is unhappy about a convenience flag for
-  #   building with profiling.
-  # - (cd xmonad-* && cabal check)
+  # cabal check
+  - (cd xmonad-* && cabal check)
 
   # haddock
   - rm -rf ./dist-newstyle
   - if $HADDOCK; then cabal new-haddock -w ${HC} ${TEST} ${BENCH} all; else echo "Skipping haddock generation";fi
 
-# REGENDATA ["xmonad.cabal"]
+  # Build without installed constraints for packages in global-db
+  - if $UNCONSTRAINED; then rm -f cabal.project.local; echo cabal new-build -w ${HC} --disable-tests --disable-benchmarks all; else echo "Not building without installed constraints"; fi
+
+# REGENDATA ["-o",".travis.yml","xmonad.cabal","libxrandr-dev"]
 # EOF