diff --git a/.circleci/config.yml b/.circleci/config.yml
index cd1416338a..f7f47dcc42 100644
--- a/.circleci/config.yml
+++ b/.circleci/config.yml
@@ -32,8 +32,8 @@ jobs:
             apt-get install -y wget gnupg golang make libgmp3-dev libtinfo-dev pkg-config zip g++ zlib1g-dev unzip python python3 bash-completion locales
             echo "en_US.UTF-8 UTF-8" >> /etc/locale.gen
             locale-gen
-            wget "https://github.com/bazelbuild/bazel/releases/download/0.24.0/bazel_0.24.0-linux-x86_64.deb"
-            dpkg -i bazel_0.24.0-linux-x86_64.deb
+            wget "https://github.com/bazelbuild/bazel/releases/download/0.27.0/bazel_0.27.0-linux-x86_64.deb"
+            dpkg -i bazel_0.27.0-linux-x86_64.deb
             echo "common:ci --build_tag_filters -requires_hackage,-requires_zlib,-requires_doctest,-requires_c2hs,-requires_threaded_rts,-dont_test_with_bindist" > .bazelrc.local
       - run:
           name: Build tests
diff --git a/azure-pipelines.yml b/azure-pipelines.yml
index d7d38059f3..c1914af575 100644
--- a/azure-pipelines.yml
+++ b/azure-pipelines.yml
@@ -9,7 +9,7 @@ jobs:
       architecture: 'x64'
   - bash: |
       set -e
-      curl -LO https://github.com/bazelbuild/bazel/releases/download/0.24.0/bazel-0.24.0-windows-x86_64.exe
+      curl -LO https://github.com/bazelbuild/bazel/releases/download/0.27.0/bazel-0.27.0-windows-x86_64.exe
       mv bazel-*.exe bazel.exe
       mkdir /c/bazel
       mv bazel.exe /c/bazel
diff --git a/shell.nix b/shell.nix
index 62bac4d8f5..693b277d8b 100644
--- a/shell.nix
+++ b/shell.nix
@@ -1,7 +1,33 @@
 { pkgs ? import ./nixpkgs {}, docTools ? true }:
 
 with pkgs;
+let
+  # WIP: bazel 0.27 upstreamable to nixpkgs
+  bazel_027 = bazel.overrideAttrs(oldAttrs: rec {
+    version = "0.27.0";
+    name = "bazel-${version}";
 
+    # WIP: needs python3 during build
+    buildInputs = oldAttrs.buildInputs ++ [pkgs.python3];
+
+    src = pkgs.fetchurl {
+      url = "https://github.com/bazelbuild/bazel/releases/download/${version}/${name}-dist.zip";
+      sha256 = "0yn662dzgfr8ls4avfl12k5sr4f210bab12wml18bh4sjlxhs263";
+    };
+
+    # Override a few /bin/bash
+    postPatch = oldAttrs.postPatch + ''
+      cat tools/build_rules/test_rules.bzl
+      substituteInPlace tools/build_rules/test_rules.bzl \
+        --replace '#!/bin/bash' '/nix/store/ya42d72dxpby7nplsya8fj7bzj3l7529-bash/bin/bash'
+
+    '';
+
+    # WIP: install check were broken on nixpkgs, I don't know what is
+    # the current status
+    doInstallCheck = false;
+  });
+in
 mkShell {
   # XXX: hack for macosX, this flags disable bazel usage of xcode
   # Note: this is set even for linux so any regression introduced by this flag
@@ -15,7 +41,7 @@ mkShell {
     which
     perl
     python3
-    bazel
+    bazel_027
     # For stack_install. TODO Remove ghc when move to Stack 2.
     stack
     ghc
@@ -49,5 +75,12 @@ mkShell {
 
     # source bazel bash completion
     source ${pkgs.bazel}/share/bash-completion/completions/bazel
+
+    # hack for ijar
+    bazel build --incompatible_disable_deprecated_attr_params=false --incompatible_new_actions_api=false --incompatible_no_support_tools_in_action_inputs=false --incompatible_require_ctx_in_configure_features=false --incompatible_depset_is_not_iterable=false --incompatible_depset_union=false --incompatible_use_python_toolchains=false @remote_java_tools_linux//:java_tools/ijar/ijar
+
+    chmod u+w  ./bazel-rules_haskell/external/remote_java_tools_linux/java_tools/ijar/ijar
+    patchelf --set-rpath ${gcc-unwrapped.lib}/lib/ ./bazel-rules_haskell/external/remote_java_tools_linux/java_tools/ijar/ijar
+    patchelf --set-interpreter ${glibc}/lib/ld-linux-x86-64.so.2 ./bazel-rules_haskell/external/remote_java_tools_linux/java_tools/ijar/ijar
   '';
 }