diff --git a/src/Swashbuckle.AspNetCore.ReDoc/Swashbuckle.AspNetCore.ReDoc.csproj b/src/Swashbuckle.AspNetCore.ReDoc/Swashbuckle.AspNetCore.ReDoc.csproj
index 90efe41080..ab861e7bf2 100644
--- a/src/Swashbuckle.AspNetCore.ReDoc/Swashbuckle.AspNetCore.ReDoc.csproj
+++ b/src/Swashbuckle.AspNetCore.ReDoc/Swashbuckle.AspNetCore.ReDoc.csproj
@@ -26,7 +26,7 @@
     <FrameworkReference Include="Microsoft.AspNetCore.App" />
   </ItemGroup>
 
-  <Target Name="NpmInstall" BeforeTargets="DispatchToInnerBuilds">
+  <Target Name="NpmInstall" BeforeTargets="DispatchToInnerBuilds" Condition=" '$(CI)' != '' OR !Exists('$(MSBuildThisFileDirectory)\node_modules') ">
     <Exec Command="npm install" ContinueOnError="true">
       <Output TaskParameter="ExitCode" PropertyName="ErrorCode" />
     </Exec>
diff --git a/src/Swashbuckle.AspNetCore.SwaggerUI/Swashbuckle.AspNetCore.SwaggerUI.csproj b/src/Swashbuckle.AspNetCore.SwaggerUI/Swashbuckle.AspNetCore.SwaggerUI.csproj
index 3e3a285f7b..10d562b646 100644
--- a/src/Swashbuckle.AspNetCore.SwaggerUI/Swashbuckle.AspNetCore.SwaggerUI.csproj
+++ b/src/Swashbuckle.AspNetCore.SwaggerUI/Swashbuckle.AspNetCore.SwaggerUI.csproj
@@ -30,7 +30,7 @@
     <FrameworkReference Include="Microsoft.AspNetCore.App" />
   </ItemGroup>
 
-  <Target Name="NpmInstall" BeforeTargets="DispatchToInnerBuilds">
+  <Target Name="NpmInstall" BeforeTargets="DispatchToInnerBuilds" Condition=" '$(CI)' != '' OR !Exists('$(MSBuildThisFileDirectory)\node_modules') ">
     <Exec Command="npm install" ContinueOnError="true">
       <Output TaskParameter="ExitCode" PropertyName="ErrorCode" />
     </Exec>