diff --git a/scripts/ci/build-release.sh b/scripts/ci/build-release.sh
index a1f58b8..572e5d2 100755
--- a/scripts/ci/build-release.sh
+++ b/scripts/ci/build-release.sh
@@ -110,13 +110,19 @@ make defconfig
 build_jobs=$(nproc)
 case $build_host in
   aarch64|arm64|armv7l|armv8l)
-    (( build_jobs <= 2 )) || build_jobs=2
+    # The x86-64 SDK host tools run through QEMU on ARM. In particular,
+    # concurrent mbedTLS links can leave partially written libraries behind;
+    # a later serial retry then packages that corrupted output. Build serially
+    # from a clean SDK extraction instead.
+    make -j1 package/openuf/compile V=sc
+    ;;
+  *)
+    if ! make -j"$build_jobs" package/openuf/compile; then
+      echo "parallel build failed; retrying serially with verbose diagnostics" >&2
+      make -j1 package/openuf/compile V=sc
+    fi
     ;;
 esac
-if ! make -j"$build_jobs" package/openuf/compile; then
-  echo "parallel build failed; retrying serially with verbose diagnostics" >&2
-  make -j1 package/openuf/compile V=sc
-fi
 
 mapfile -t packages < <(find bin/packages -type f -name "openuf-${version}-*.apk")
 if [[ ${#packages[@]} -ne 1 ]]; then