diff --git a/src/Runner.Common/HostContext.cs b/src/Runner.Common/HostContext.cs
index d4ea48c..2ec8455 100644
--- a/src/Runner.Common/HostContext.cs
+++ b/src/Runner.Common/HostContext.cs
@@ -220,12 +220,13 @@ namespace GitHub.Runner.Common
 
                 case WellKnownDirectory.Externals:
                     path = Path.Combine(
-                        GetDirectory(WellKnownDirectory.Root),
+                        new DirectoryInfo(GetDirectory(WellKnownDirectory.Bin)).Parent.FullName,
                         Constants.Path.ExternalsDirectory);
                     break;
 
                 case WellKnownDirectory.Root:
-                    path = new DirectoryInfo(GetDirectory(WellKnownDirectory.Bin)).Parent.FullName;
+                    path = Environment.GetEnvironmentVariable("RUNNER_ROOT")
+                                ?? new DirectoryInfo(GetDirectory(WellKnownDirectory.Bin)).Parent.FullName;
                     break;
 
                 case WellKnownDirectory.Temp: