diff --git a/.vsts-ci.Windows.yml b/.vsts-ci.Windows.yml
index 6cc06371..5e0fd618 100644
--- a/.vsts-ci.Windows.yml
+++ b/.vsts-ci.Windows.yml
@@ -4,6 +4,9 @@ jobs:
   pool:
     vmImage: 'windows-2019'
 
+  variables:
+    NDK_ROOT: C:\Microsoft\AndroidNDK64\android-ndk-r19c
+
   steps:
   - task: GitVersion@4
     inputs:
diff --git a/src/CalcManager.Android/CalcManager.Android.vcxproj b/src/CalcManager.Android/CalcManager.Android.vcxproj
index 9b9c131e..dd55a9db 100644
--- a/src/CalcManager.Android/CalcManager.Android.vcxproj
+++ b/src/CalcManager.Android/CalcManager.Android.vcxproj
@@ -105,49 +105,49 @@
     <ConfigurationType>DynamicLibrary</ConfigurationType>
     <UseDebugLibraries>true</UseDebugLibraries>
     <PlatformToolset>Clang_5_0</PlatformToolset>
-    <AndroidAPILevel>android-27</AndroidAPILevel>
+    <AndroidAPILevel>android-21</AndroidAPILevel>
   </PropertyGroup>
   <PropertyGroup Condition="'$(Configuration)|$(Platform)'=='Release|ARM64'" Label="Configuration">
     <ConfigurationType>DynamicLibrary</ConfigurationType>
     <UseDebugLibraries>false</UseDebugLibraries>
     <PlatformToolset>Clang_5_0</PlatformToolset>
-    <AndroidAPILevel>android-27</AndroidAPILevel>
+    <AndroidAPILevel>android-21</AndroidAPILevel>
   </PropertyGroup>
   <PropertyGroup Condition="'$(Configuration)|$(Platform)'=='Debug|ARM'" Label="Configuration">
     <ConfigurationType>DynamicLibrary</ConfigurationType>
     <UseDebugLibraries>true</UseDebugLibraries>
     <PlatformToolset>Clang_5_0</PlatformToolset>
-    <AndroidAPILevel>android-27</AndroidAPILevel>
+    <AndroidAPILevel>android-21</AndroidAPILevel>
   </PropertyGroup>
   <PropertyGroup Condition="'$(Configuration)|$(Platform)'=='Release|ARM'" Label="Configuration">
     <ConfigurationType>DynamicLibrary</ConfigurationType>
     <UseDebugLibraries>false</UseDebugLibraries>
     <PlatformToolset>Clang_5_0</PlatformToolset>
-    <AndroidAPILevel>android-27</AndroidAPILevel>
+    <AndroidAPILevel>android-21</AndroidAPILevel>
   </PropertyGroup>
   <PropertyGroup Condition="'$(Configuration)|$(Platform)'=='Debug|x64'" Label="Configuration">
     <ConfigurationType>DynamicLibrary</ConfigurationType>
     <UseDebugLibraries>true</UseDebugLibraries>
     <PlatformToolset>Clang_5_0</PlatformToolset>
-    <AndroidAPILevel>android-27</AndroidAPILevel>
+    <AndroidAPILevel>android-21</AndroidAPILevel>
   </PropertyGroup>
   <PropertyGroup Condition="'$(Configuration)|$(Platform)'=='Release|x64'" Label="Configuration">
     <ConfigurationType>DynamicLibrary</ConfigurationType>
     <UseDebugLibraries>false</UseDebugLibraries>
     <PlatformToolset>Clang_5_0</PlatformToolset>
-    <AndroidAPILevel>android-27</AndroidAPILevel>
+    <AndroidAPILevel>android-21</AndroidAPILevel>
   </PropertyGroup>
   <PropertyGroup Condition="'$(Configuration)|$(Platform)'=='Debug|x86'" Label="Configuration">
     <ConfigurationType>DynamicLibrary</ConfigurationType>
     <UseDebugLibraries>true</UseDebugLibraries>
     <PlatformToolset>Clang_5_0</PlatformToolset>
-    <AndroidAPILevel>android-27</AndroidAPILevel>
+    <AndroidAPILevel>android-21</AndroidAPILevel>
   </PropertyGroup>
   <PropertyGroup Condition="'$(Configuration)|$(Platform)'=='Release|x86'" Label="Configuration">
     <ConfigurationType>DynamicLibrary</ConfigurationType>
     <UseDebugLibraries>false</UseDebugLibraries>
     <PlatformToolset>Clang_5_0</PlatformToolset>
-    <AndroidAPILevel>android-27</AndroidAPILevel>
+    <AndroidAPILevel>android-21</AndroidAPILevel>
   </PropertyGroup>
   <Import Project="$(VCTargetsPath)/Microsoft.Cpp.props" />
   <ImportGroup Label="ExtensionSettings" />