diff --git a/config/BUILDCONFIG.gn b/config/BUILDCONFIG.gn
index dc24744..538f72e 100644
--- a/config/BUILDCONFIG.gn
+++ b/config/BUILDCONFIG.gn
@@ -61,18 +61,32 @@
   # See //build/toolchain/clang_toolchain.gni for details.
   current_base_toolchain = target_toolchain
 
-  # zircon build project
+  # Zircon projects to target - must match the target architecture.
+  zircon_projects = []
+
+  # DEPRECATED: zircon build project
+  # Use zircon_projects instead
   zircon_project = ""
 }
 
-if (zircon_project == "") {
+if (zircon_project != "") {
+  assert(zircon_projects == [], "Use zircon_projects instead of zircon_project")
+  zircon_projects = [ zircon_project ]
+} else if (zircon_projects == []) {
   if (current_cpu == "arm64") {
-    zircon_project = "zircon-qemu-arm64"
+    zircon_projects = [ "zircon-qemu-arm64" ]
   } else if (current_cpu == "x64") {
-    zircon_project = "zircon-pc-x86-64"
+    zircon_projects = [ "zircon-pc-x86-64" ]
   }
 }
-assert(zircon_project != "", "unable to set default zircon build project")
+if (target_cpu == "x64") {
+  zircon_sysroot =
+      rebase_path("//out/build-zircon/build-zircon-pc-x86-64/sysroot")
+} else {
+  assert(target_cpu == "arm64", "Unsupported target architecture $target_cpu")
+  zircon_sysroot =
+      rebase_path("//out/build-zircon/build-zircon-qemu-arm64/sysroot")
+}
 
 is_android = false
 is_fuchsia = false
diff --git a/config/sysroot.gni b/config/sysroot.gni
index fbe3fc1..20c924b 100644
--- a/config/sysroot.gni
+++ b/config/sysroot.gni
@@ -10,7 +10,7 @@
 if (current_os == target_os && target_sysroot != "") {
   sysroot = target_sysroot
 } else if (is_fuchsia) {
-  sysroot = rebase_path("//out/build-zircon/build-${zircon_project}/sysroot")
+  sysroot = zircon_sysroot
 } else if (is_linux) {
   sysroot = rebase_path("//buildtools/sysroot")
 } else if (is_mac) {
diff --git a/go/build.py b/go/build.py
index b5919ad..89a1cec 100755
--- a/go/build.py
+++ b/go/build.py
@@ -20,7 +20,7 @@
                         required=True)
     parser.add_argument('--root-out-dir', help='Path to root of build output',
                         required=True)
-    parser.add_argument('--zircon-build-dir', help='The Zircon build dir to use',
+    parser.add_argument('--zircon-sysroot', help='The Zircon sysroot to use',
                         required=True)
     parser.add_argument('--depfile', help='The path to the depfile',
                         required=True)
@@ -87,7 +87,7 @@
     env['GOARCH'] = goarch
     env['GOOS'] = goos
     env['GOPATH'] = gopath
-    env['ZIRCON_BUILD_DIR'] = args.zircon_build_dir
+    env['ZIRCON_SYSROOT'] = args.zircon_sysroot
 
     # /usr/bin:/bin are required for basic things like bash(1) and env(1), but
     # preference the toolchain path. Note that on Mac, ld is also found from
diff --git a/go/go_build.gni b/go/go_build.gni
index fdfe347..2d2eb63 100644
--- a/go/go_build.gni
+++ b/go/go_build.gni
@@ -48,7 +48,9 @@
     use_strip = is_fuchsia
 
     output_path = "${root_out_dir}/${output_name}"
-    outputs = [ output_path ]
+    outputs = [
+      output_path,
+    ]
 
     if (use_strip) {
       unstripped_output_path = "${root_out_dir}/exe.unstripped/${output_name}"
@@ -72,8 +74,8 @@
       rebase_path("//."),
       "--root-out-dir",
       rebase_path(root_out_dir, root_build_dir),
-      "--zircon-build-dir",
-      rebase_path("//out/build-zircon/build-${zircon_project}"),
+      "--zircon-sysroot",
+      rebase_path(zircon_sysroot),
       "--depfile",
       rebase_path(depfile),
       "--current-cpu",
@@ -89,7 +91,10 @@
     ]
 
     if (use_strip) {
-      args += [ "--unstripped-binname", "exe.unstripped/${output_name}" ]
+      args += [
+        "--unstripped-binname",
+        "exe.unstripped/${output_name}",
+      ]
     }
 
     if (defined(invoker.test) && invoker.test) {