diff --git a/azure-pipelines.yml b/azure-pipelines.yml
index 5a7c6acdc..483f1eb2b 100644
--- a/azure-pipelines.yml
+++ b/azure-pipelines.yml
@@ -86,6 +86,7 @@ jobs:
         zlib-devel
       displayName: Install Dependencies
     - script: |
+        set BOOST_ROOT=
         set PATH=%CYGWIN_ROOT%\bin;%SYSTEMROOT%\system32
         cp /usr/bin/python3.5 /usr/bin/python3
         env.exe -- python3 run_tests.py --backend=ninja
@@ -150,6 +151,7 @@ jobs:
         %TOOLCHAIN%
       displayName: Install Dependencies
     - script: |
+        set BOOST_ROOT=
         set PATH=%SystemRoot%\system32;%SystemRoot%;%SystemRoot%\System32\Wbem
         set PATHEXT=%PATHEXT%;.py
         if %compiler%==clang ( set CC=clang && set CXX=clang++ )
diff --git a/ci/azure-steps.yml b/ci/azure-steps.yml
index 6fe1831e0..7e0f6fe3c 100644
--- a/ci/azure-steps.yml
+++ b/ci/azure-steps.yml
@@ -71,6 +71,8 @@ steps:
        Start-Process "boost_$boost_filename-msvc-$boost_abi_tag-$boost_bitness.exe" -ArgumentList "/dir=$(System.WorkFolder)\boost_$boost_filename /silent" -Wait
        $env:BOOST_ROOT = "$(System.WorkFolder)\boost_$boost_filename"
        $env:Path = "$env:Path;$env:BOOST_ROOT\lib$boost_bitness-msvc-$boost_abi_tag"
+     } else {
+       $env:BOOST_ROOT = ""
      }
 
      # install D compiler and dub packages