diff --git a/src/Misc/externals.sh b/src/Misc/externals.sh
index 69f90c627..46ea4b845 100755
--- a/src/Misc/externals.sh
+++ b/src/Misc/externals.sh
@@ -136,18 +136,23 @@ if [[ "$PACKAGERUNTIME" == "osx-x64" ]]; then
     acquireExternalTool "$NODE_URL/v${NODE12_VERSION}/node-v${NODE12_VERSION}-darwin-x64.tar.gz" node12 fix_nested_dir
 fi
 
-# TODO make sure linux[x64, x84, arm64(8), arm32(7)] are listed
-# Download the external tools common across Linux PACKAGERUNTIMEs (excluding OSX).
+# Download the external tools for Linux PACKAGERUNTIMEs.
 if [[ "$PACKAGERUNTIME" == "linux-x64" || "$PACKAGERUNTIME" == "rhel.6-x64" ]]; then
     acquireExternalTool "$NODE_URL/v${NODE12_VERSION}/node-v${NODE12_VERSION}-linux-x64.tar.gz" node12 fix_nested_dir
     # TODO: Repath this blob to use a consistent version format (_ vs .)
     acquireExternalTool "https://vstsagenttools.blob.core.windows.net/tools/nodejs/12_4_0/alpine/node-v${NODE12_VERSION}-alpine.tar.gz" node12_alpine
+    # acquireExternalTool "https://vstsagenttools.blob.core.windows.net/tools/nodejs/12.13.0/alpine/x64/node-v${NODE12_VERSION}-alpine-x64.tar.gz" node12_alpine
 fi
 
 if [[ "$PACKAGERUNTIME" == "linux-arm64" ]]; then
     acquireExternalTool "$NODE_URL/v${NODE12_VERSION}/node-v${NODE12_VERSION}-linux-arm64.tar.gz" node12 fix_nested_dir
+    # TODO: alpine node runtime for arm64(8)
+    # acquireExternalTool "https://vstsagenttools.blob.core.windows.net/tools/nodejs/12.13.0/alpine/arm64/node-v${NODE12_VERSION}-alpine-arm64.tar.gz" node12_alpine
 fi
 
 if [[ "$PACKAGERUNTIME" == "linux-arm" ]]; then
     acquireExternalTool "$NODE_URL/v${NODE12_VERSION}/node-v${NODE12_VERSION}-linux-armv7l.tar.gz" node12 fix_nested_dir
+    # TODO: alpine node runtime for arm32(7)
+    # Need to set up custom gcc toolchain to cross compile on x64 ubuntu for armv7 (per https://github.com/nodejs/node/blob/master/BUILDING.md)
+    # acquireExternalTool "https://vstsagenttools.blob.core.windows.net/tools/nodejs/12.13.0/alpine/arm/node-v${NODE12_VERSION}-alpine-arm.tar.gz" node12_alpine
 fi
diff --git a/src/Runner.Common/Util/VarUtil.cs b/src/Runner.Common/Util/VarUtil.cs
index 81b8ecb23..b9860e151 100644
--- a/src/Runner.Common/Util/VarUtil.cs
+++ b/src/Runner.Common/Util/VarUtil.cs
@@ -54,6 +54,8 @@ namespace GitHub.Runner.Common.Util
                         return "X64";
                     case Constants.Architecture.Arm:
                         return "ARM";
+                    case Constants.Architecture.Arm64:
+                        return "ARM64";
                     default:
                         throw new NotSupportedException(); // Should never reach here.
                 }
diff --git a/src/Test/L0/ConstantGenerationL0.cs b/src/Test/L0/ConstantGenerationL0.cs
index 7e9fcb0d3..7b6619730 100644
--- a/src/Test/L0/ConstantGenerationL0.cs
+++ b/src/Test/L0/ConstantGenerationL0.cs
@@ -18,6 +18,7 @@ namespace GitHub.Runner.Common.Tests
                 "win-x86",
                 "linux-x64",
                 "linux-arm",
+                "linux-arm64",
                 "rhel.6-x64",
                 "osx-x64"
             };