diff --git a/.azure/linux-stack.yml b/.azure/linux-stack.yml
index ec12e3f7..404abaec 100644
--- a/.azure/linux-stack.yml
+++ b/.azure/linux-stack.yml
@@ -13,12 +13,6 @@ jobs:
         YAML_FILE: stack-8.6.5.yaml
       stack-8.6.4:
         YAML_FILE: stack-8.6.4.yaml
-      stack-8.6.3:
-        YAML_FILE: stack-8.6.3.yaml
-      stack-8.6.2:
-        YAML_FILE: stack-8.6.2.yaml
-      stack-8.6.1:
-        YAML_FILE: stack-8.6.1.yaml
       stack-8.4.4:
         YAML_FILE: stack-8.4.4.yaml
       stack-8.4.3:
@@ -65,7 +59,7 @@ jobs:
       source .azure/linux-stack.bashrc
       stack install --stack-yaml $(YAML_FILE) # `hie` binary required locally for tests
       mkdir .azure-deploy
-      stack install --stack-yaml $(YAML_FILE) --local-bin-path .azure-deploy 
+      stack install --stack-yaml $(YAML_FILE) --local-bin-path .azure-deploy
       cd .azure-deploy
       if [ $YAML_FILE != "stack.yaml" ]; then
         GHC_MINOR_VERSION=${YAML_FILE:6:5}
@@ -80,7 +74,7 @@ jobs:
       cp "$(Agent.TempDirectory)"/hlint*/data/hlint.yaml data
       ARTIFACT_NAME=hie-$(hie --numeric-version)-ghc-$GHC_MINOR_VERSION-linux-x86_64
       tar -vczf $(Build.ArtifactStagingDirectory)/$ARTIFACT_NAME.tar.xz *
-    displayName: Install `hie` 
+    displayName: Install `hie`
   - bash: |
       source .azure/linux-stack.bashrc
       stack build --stack-yaml $(YAML_FILE) --test --bench --only-dependencies
diff --git a/.azure/macos-stack.yml b/.azure/macos-stack.yml
index 1f63b3ab..475d93ed 100644
--- a/.azure/macos-stack.yml
+++ b/.azure/macos-stack.yml
@@ -13,8 +13,6 @@ jobs:
         YAML_FILE: stack-8.6.5.yaml
       stack-8.6.4:
         YAML_FILE: stack-8.6.4.yaml
-      stack-8.6.3:
-        YAML_FILE: stack-8.6.3.yaml
       stack-8.4.4:
         YAML_FILE: stack-8.4.4.yaml
       stack-8.4.3:
@@ -62,7 +60,7 @@ jobs:
       source .azure/macos.bashrc
       stack install --stack-yaml $(YAML_FILE) # `hie` binary required locally for tests
       mkdir .azure-deploy
-      stack install --stack-yaml $(YAML_FILE) --local-bin-path .azure-deploy 
+      stack install --stack-yaml $(YAML_FILE) --local-bin-path .azure-deploy
       cd .azure-deploy
       if [ $YAML_FILE != "stack.yaml" ]; then
         GHC_MINOR_VERSION=${YAML_FILE:6:5}
@@ -77,7 +75,7 @@ jobs:
       cp "$(Agent.TempDirectory)"/hlint*/data/hlint.yaml data
       ARTIFACT_NAME=hie-$(hie --numeric-version)-ghc-$GHC_MINOR_VERSION-macos-x86_64
       tar -vczf $(Build.ArtifactStagingDirectory)/$ARTIFACT_NAME.tar.xz *
-    displayName: Install `hie` 
+    displayName: Install `hie`
   - bash: |
       source .azure/macos.bashrc
       stack build --stack-yaml $(YAML_FILE) --test --bench --only-dependencies
diff --git a/.azure/windows-stack.yml b/.azure/windows-stack.yml
index d5a02aac..c7379536 100644
--- a/.azure/windows-stack.yml
+++ b/.azure/windows-stack.yml
@@ -12,10 +12,6 @@ jobs:
         YAML_FILE: stack-8.6.5.yaml
       stack-8.6.4:
         YAML_FILE: stack-8.6.4.yaml
-      stack-8.6.2:
-        YAML_FILE: stack-8.6.2.yaml
-      stack-8.6.1:
-        YAML_FILE: stack-8.6.1.yaml
       stack-8.4.4:
         YAML_FILE: stack-8.4.4.yaml
       stack-8.4.3:
@@ -63,7 +59,7 @@ jobs:
       source .azure/windows.bashrc
       stack install --stack-yaml $(YAML_FILE) # `hie` binary required locally for tests
       mkdir .azure-deploy
-      stack install --stack-yaml $(YAML_FILE) --local-bin-path .azure-deploy 
+      stack install --stack-yaml $(YAML_FILE) --local-bin-path .azure-deploy
       cd .azure-deploy
       if [ $YAML_FILE != "stack.yaml" ]; then
         GHC_MINOR_VERSION=${YAML_FILE:6:5}
@@ -78,7 +74,7 @@ jobs:
       cp "$(Agent.TempDirectory)"/hlint*/data/hlint.yaml data
       ARTIFACT_NAME=hie-$(hie --numeric-version)-ghc-$GHC_MINOR_VERSION-windows-x86_64
       7z a "$(Build.ArtifactStagingDirectory)/$ARTIFACT_NAME.zip" *
-    displayName: Install `hie` 
+    displayName: Install `hie`
   - bash: |
       source .azure/windows.bashrc
       stack build --stack-yaml $(YAML_FILE) --test --bench --only-dependencies
@@ -128,4 +124,3 @@ jobs:
       tar -vczf .azure-cache/stack-root.tar.gz $(cygpath $STACK_ROOT)
       tar -vczf .azure-cache/stack-work.tar.gz .stack-work
     displayName: "Pack cache"
-  
\ No newline at end of file
diff --git a/.circleci/config.yml b/.circleci/config.yml
index 769c515c..bd3312b1 100644
--- a/.circleci/config.yml
+++ b/.circleci/config.yml
@@ -116,21 +116,6 @@ jobs:
       - STACK_FILE: "stack-8.4.4.yaml"
     <<: *defaults
 
-  ghc-8.6.1:
-    environment:
-      - STACK_FILE: "stack-8.6.1.yaml"
-    <<: *defaults
-
-  ghc-8.6.2:
-    environment:
-      - STACK_FILE: "stack-8.6.2.yaml"
-    <<: *defaults
-
-  ghc-8.6.3:
-    environment:
-      - STACK_FILE: "stack-8.6.3.yaml"
-    <<: *defaults
-
   ghc-8.6.4:
     environment:
       - STACK_FILE: "stack-8.6.4.yaml"
@@ -184,9 +169,6 @@ workflows:
       - ghc-8.4.2
       - ghc-8.4.3
       - ghc-8.4.4
-      - ghc-8.6.1
-      - ghc-8.6.2
-      # - ghc-8.6.3
       - ghc-8.6.4
       - ghc-8.6.5
       - ghc-nightly
diff --git a/appveyor.yml b/appveyor.yml
index e45e2ca1..1a8f04e1 100644
--- a/appveyor.yml
+++ b/appveyor.yml
@@ -1,9 +1,7 @@
 version: 1.0.{build}
 environment:
   matrix:
-#  - GHCVER: 8.6.4
-  - GHCVER: 8.6.2
-  - GHCVER: 8.6.1
+  - GHCVER: 8.6.5
   - GHCVER: 8.4.4
   - GHCVER: 8.4.3
   - GHCVER: 8.4.2
diff --git a/stack-8.6.1.yaml b/stack-8.6.1.yaml
deleted file mode 100644
index bc5e343f..00000000
--- a/stack-8.6.1.yaml
+++ /dev/null
@@ -1,65 +0,0 @@
-resolver: nightly-2018-11-11 # Last GHC 8.6.1
-packages:
-  - .
-  - hie-plugin-api
-
-extra-deps:
-# - ./submodules/HaRe
-
-- apply-refact-0.6.0.0
-- brittany-0.12.1.0
-- butcher-1.3.2.3
-- bytestring-trie-0.2.5.0
-- cabal-helper-1.0.0.0
-- cabal-install-2.4.0.0
-- cabal-plan-0.5.0.0
-- constrained-dynamic-0.1.0.0
-- czipwith-1.0.1.1
-- data-tree-print-0.1.0.2
-- deque-0.4.3
-- extra-1.6.18
-- filepattern-0.1.1
-- floskell-0.10.2
-- ghc-exactprint-0.6.2 # for HaRe
-- ghc-lib-parser-8.8.1
-- ghc-lib-parser-ex-8.8.2
-- haddock-api-2.21.0
-- haskell-lsp-0.19.0.0
-- haskell-lsp-types-0.19.0.0
-- haskell-src-exts-1.21.1
-- haskell-src-exts-util-0.2.5
-- hie-bios-0.3.2
-- hlint-2.2.8
-- hoogle-5.0.17.11
-- hsimport-0.11.0
-- libyaml-0.1.1.0
-- lsp-test-0.10.0.0
-- monad-dijkstra-0.1.1.2
-- monad-memo-0.4.1
-- monoid-subclasses-0.4.6.1
-- multistate-0.8.0.1
-- parser-combinators-1.2.1
-- ormolu-0.0.3.0
-- primes-0.2.1.0
-- resolv-0.1.1.2
-- rope-utf16-splay-0.3.1.0
-- strict-list-0.1.5
-- syz-0.2.0.0
-- temporary-1.2.1.1
-- unix-compat-0.5.2
-- unordered-containers-0.2.10.0
-- yaml-0.11.1.2
-
-# To make build work in windows 7
-- unix-time-0.4.7
-
-flags:
-  haskell-ide-engine:
-    pedantic: true
-  hie-plugin-api:
-    pedantic: true
-
-nix:
-  packages: [ icu libcxx zlib ]
-
-concurrent-tests: false
diff --git a/stack-8.6.2.yaml b/stack-8.6.2.yaml
deleted file mode 100644
index be019477..00000000
--- a/stack-8.6.2.yaml
+++ /dev/null
@@ -1,59 +0,0 @@
-resolver: nightly-2018-12-17 # Last GHC 8.6.2
-packages:
-  - .
-  - hie-plugin-api
-
-extra-deps:
-# - ./submodules/HaRe
-
-- brittany-0.12.1.0
-- butcher-1.3.2.3
-- bytestring-trie-0.2.5.0
-- cabal-helper-1.0.0.0
-- cabal-plan-0.5.0.0
-- constrained-dynamic-0.1.0.0
-- deque-0.4.3
-- extra-1.6.18
-- filepattern-0.1.1
-- floskell-0.10.2
-- ghc-exactprint-0.6.2 # for HaRe
-- ghc-lib-parser-8.8.1
-- ghc-lib-parser-ex-8.8.2
-- haddock-api-2.21.0
-- haskell-lsp-0.19.0.0
-- haskell-lsp-types-0.19.0.0
-- haskell-src-exts-1.21.1
-- haskell-src-exts-util-0.2.5
-- hie-bios-0.3.2
-- hlint-2.2.8
-- hoogle-5.0.17.11
-- hsimport-0.11.0
-- libyaml-0.1.1.0
-- lsp-test-0.10.0.0
-- monad-dijkstra-0.1.1.2
-- monad-memo-0.4.1
-- multistate-0.8.0.1
-- parser-combinators-1.2.1
-- ormolu-0.0.3.0
-- rope-utf16-splay-0.3.1.0
-- strict-list-0.1.5
-- syz-0.2.0.0
-- temporary-1.2.1.1
-- unix-compat-0.5.2
-- unordered-containers-0.2.10.0
-- yaml-0.11.1.2
-# To make build work in windows 7
-- unix-time-0.4.7
-#- hie-bios-0.2.1@sha256:5f98a3516ce65e0a3ffd88bf6fb416b04cc084371d0fbf0e1762780de1d652ce,3219
-
-
-flags:
-  haskell-ide-engine:
-    pedantic: true
-  hie-plugin-api:
-    pedantic: true
-
-nix:
-  packages: [ icu libcxx zlib ]
-
-concurrent-tests: false
diff --git a/stack-8.6.3.yaml b/stack-8.6.3.yaml
deleted file mode 100644
index 012836a3..00000000
--- a/stack-8.6.3.yaml
+++ /dev/null
@@ -1,55 +0,0 @@
-resolver: lts-13.10 # Last GHC 8.6.3
-packages:
-  - .
-  - hie-plugin-api
-
-extra-deps:
-# - ./submodules/HaRe
-
-- brittany-0.12.1.0
-- butcher-1.3.2.1
-- bytestring-trie-0.2.5.0
-- cabal-helper-1.0.0.0
-- cabal-plan-0.5.0.0
-- constrained-dynamic-0.1.0.0
-- extra-1.6.18
-- floskell-0.10.2
-- ghc-exactprint-0.6.2 # for HaRe
-- ghc-lib-parser-8.8.1
-- ghc-lib-parser-ex-8.8.2
-- haddock-api-2.21.0
-- haskell-lsp-0.19.0.0
-- haskell-lsp-types-0.19.0.0
-- haskell-src-exts-1.21.1
-- haskell-src-exts-util-0.2.5
-- hie-bios-0.3.2
-- hlint-2.2.8
-- hoogle-5.0.17.11
-- hsimport-0.11.0
-- lsp-test-0.10.0.0
-- monad-dijkstra-0.1.1.2
-- monad-memo-0.4.1
-- multistate-0.8.0.1
-- optparse-simple-0.1.0
-- ormolu-0.0.3.0
-- parser-combinators-1.2.1
-- rope-utf16-splay-0.3.1.0
-- syz-0.2.0.0
-- temporary-1.2.1.1
-- unix-compat-0.5.2
-- unordered-containers-0.2.10.0
-- yaml-0.11.1.2
-
-# To make build work in windows 7
-- unix-time-0.4.7
-
-flags:
-  haskell-ide-engine:
-    pedantic: true
-  hie-plugin-api:
-    pedantic: true
-
-nix:
-  packages: [ icu libcxx zlib ]
-
-concurrent-tests: false