diff --git a/.travis.yml b/.travis.yml
index 116dd4329053096ab451023660dfff089dea5470..ed798ab5cbb466fd67ba3a0e8b0bdd9cc908fc25 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -28,6 +28,9 @@ before_cache:
 
 matrix:
   include:
+    - compiler: "ghc-8.6.1"
+      env: GHCHEAD=true
+      addons: {apt: {packages: [ghc-ppa-tools,cabal-install-head,ghc-8.6.1], sources: [hvr-ghc]}}
     - compiler: "ghc-8.4.3"
     # env: TEST=--disable-tests BENCH=--disable-benchmarks
       addons: {apt: {packages: [ghc-ppa-tools,cabal-install-2.2,ghc-8.4.3], sources: [hvr-ghc]}}
@@ -55,7 +58,7 @@ matrix:
       addons: {apt: {packages: [ghc-ppa-tools,cabal-install-2.2,ghc-7.2.2], sources: [hvr-ghc]}}
     - compiler: "ghc-7.0.4"
     # can't build the testsuites dependencies with 7.0
-      env: INSTALLED=false TEST=--disable-tests BENCH=--disable-benchmarks
+      env: UNCONSTRAINED=false TEST=--disable-tests BENCH=--disable-benchmarks
       addons: {apt: {packages: [ghc-ppa-tools,cabal-install-2.2,ghc-7.0.4], sources: [hvr-ghc]}}
     - compiler: "ghc-head"
       env: GHCHEAD=true
@@ -63,6 +66,7 @@ matrix:
 
   allow_failures:
     - compiler: "ghc-head"
+    - compiler: "ghc-8.6.1"
 
 before_install:
   - HC=${CC}
@@ -80,7 +84,8 @@ install:
   - BENCH=${BENCH---enable-benchmarks}
   - TEST=${TEST---enable-tests}
   - HADDOCK=${HADDOCK-true}
-  - INSTALLED=${INSTALLED-true}
+  - UNCONSTRAINED=${UNCONSTRAINED-true}
+  - NOINSTALLEDCONSTRAINTS=${NOINSTALLEDCONSTRAINTS-false}
   - GHCHEAD=${GHCHEAD-false}
   - travis_retry cabal update -v
   - "sed -i.bak 's/^jobs:/-- jobs:/' ${HOME}/.cabal/config"
@@ -88,7 +93,8 @@ install:
   # Overlay Hackage Package Index for GHC HEAD: https://github.com/hvr/head.hackage
   - |
     if $GHCHEAD; then
-      sed -i.bak 's/-- allow-newer:.*/allow-newer: *:base, *:template-haskell, *:ghc, *:Cabal/' ${HOME}/.cabal/config
+      sed -i 's/-- allow-newer: .*/allow-newer: *:base/' ${HOME}/.cabal/config
+      for pkg in $($HCPKG list --simple-output); do pkg=$(echo $pkg | sed 's/-[^-]*$//'); sed -i "s/allow-newer: /allow-newer: *:$pkg, /" ${HOME}/.cabal/config; done
 
       echo 'repository head.hackage'                                                        >> ${HOME}/.cabal/config
       echo '   url: http://head.hackage.haskell.org/'                                       >> ${HOME}/.cabal/config
@@ -98,11 +104,16 @@ install:
       echo '              8f79fd2389ab2967354407ec852cbe73f2e8635793ac446d09461ffb99527f6e' >> ${HOME}/.cabal/config
       echo '   key-threshold: 3'                                                            >> ${HOME}/.cabal.config
 
+      grep -Ev -- '^\s*--' ${HOME}/.cabal/config | grep -Ev '^\s*$'
+
       cabal new-update head.hackage -v
     fi
   - grep -Ev -- '^\s*--' ${HOME}/.cabal/config | grep -Ev '^\s*$'
   - "printf 'packages: \".\"\\n' > cabal.project"
-  - cat cabal.project
+  - touch cabal.project.local
+  - "if ! $NOINSTALLEDCONSTRAINTS; then for pkg in $($HCPKG list --simple-output); do echo $pkg | sed 's/^/constraints: /' | sed 's/-[^-]*$/ installed/' >> cabal.project.local; done; fi"
+  - cat cabal.project || true
+  - cat cabal.project.local || true
   - if [ -f "./configure.ac" ]; then
       (cd "." && autoreconf -i);
     fi
@@ -121,13 +132,13 @@ script:
   - cd ${DISTDIR} || false
   - find . -maxdepth 1 -name '*.tar.gz' -exec tar -xvf '{}' \;
   - "printf 'packages: hsc2hs-*/*.cabal\\n' > cabal.project"
-  - cat cabal.project
+  - touch cabal.project.local
+  - "if ! $NOINSTALLEDCONSTRAINTS; then for pkg in $($HCPKG list --simple-output); do echo $pkg | sed 's/^/constraints: /' | sed 's/-[^-]*$/ 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
@@ -135,5 +146,8 @@ script:
   # cabal check
   - (cd hsc2hs-* && cabal check)
 
+  # 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","--ghc-head","cabal.project"]
 # EOF
diff --git a/hsc2hs.cabal b/hsc2hs.cabal
index 10b0cefdd7c55934bfbc563a8c3ccaf9cdc6b4d2..d5333249192a5e70795d6addcc592684c72ea2b7 100644
--- a/hsc2hs.cabal
+++ b/hsc2hs.cabal
@@ -23,7 +23,7 @@ Category: Development
 Data-Files: template-hsc.h
 build-type: Simple
 cabal-version: >=1.10
-tested-with: GHC==8.4.3, GHC==8.2.2, GHC==8.0.2, GHC==7.10.3, GHC==7.8.4, GHC==7.6.3, GHC==7.4.2, GHC==7.2.2, GHC==7.0.4
+tested-with: GHC==8.6.1, GHC==8.4.3, GHC==8.2.2, GHC==8.0.2, GHC==7.10.3, GHC==7.8.4, GHC==7.6.3, GHC==7.4.2, GHC==7.2.2, GHC==7.0.4
 
 extra-source-files:
   changelog.md