diff --git a/default.nix b/default.nix
index 3161c5363..cde49c475 100644
--- a/default.nix
+++ b/default.nix
@@ -57,7 +57,10 @@ let
       if system == "x86_64-linux" && crossSystem == null && enableStatic then
         "x86_64-unknown-linux-musl"
       else
-        crossSystem;
+        if system == "aarch64-linux" && crossSystem == null && enableStatic then
+          "aarch64-unknown-linux-musl"
+        else
+          crossSystem;
   };
 
   # Use nixpkgs' top-level/static overlay if enableStatic = true.
diff --git a/nix/default.nix b/nix/default.nix
index 7819ffbb3..627b3eba7 100644
--- a/nix/default.nix
+++ b/nix/default.nix
@@ -25,6 +25,7 @@ let
       (import ./overlays/native.nix)
       # Specific overrides guarded by the host platform.
       (import ./overlays/musl.nix)
+      (import ./overlays/arm.nix)
     ];
   };
 
diff --git a/nix/overlays/arm.nix b/nix/overlays/arm.nix
index 62bb1eb0d..36c29d9bc 100644
--- a/nix/overlays/arm.nix
+++ b/nix/overlays/arm.nix
@@ -6,7 +6,7 @@ let
 
 in prev.lib.optionalAttrs isAarch64 {
   libsigsegv = prev.libsigsegv.overrideAttrs (attrs: {
-    preConfigure = (old.preConfigure or "") + ''
+    preConfigure = (prev.preConfigure or "") + ''
       sed -i 's/^CFG_FAULT=$/CFG_FAULT=fault-linux-arm.h/' configure
     '';
   });
diff --git a/pkg/urbit/include/c/portable.h b/pkg/urbit/include/c/portable.h
index 10c2aa710..83871d32f 100644
--- a/pkg/urbit/include/c/portable.h
+++ b/pkg/urbit/include/c/portable.h
@@ -113,8 +113,7 @@
 #   if defined(U3_OS_linux)
 #     ifdef __LP64__
 #       ifdef U3_CPU_aarch64
-//  XX not yet
-//#         define U3_OS_ARCH "aarch64-linux"
+#         define U3_OS_ARCH "aarch64-linux"
 #       else
 #         define U3_OS_ARCH "x86_64-linux"
 #       endif