diff --git a/.circleci/config.yml b/.circleci/config.yml
index 7e8bd8170a..3914da46d7 100644
--- a/.circleci/config.yml
+++ b/.circleci/config.yml
@@ -39,16 +39,12 @@ jobs:
           name: Install clang-format
           command: |
             apt-get update -y
-            apt-get install -y wget
-            apt install -y lsb-release wget software-properties-common gnupg
-            wget https://apt.llvm.org/llvm.sh
-            chmod u+x llvm.sh
-            ./llvm.sh 18
-            apt-get install -y git-core clang-format-18
+            apt-get install -y curl tar gzip
+            bash .circleci/setup-clang-format.sh
       - run:
           name: Verify clang-format
           command: |
-             git ls-files | grep -E  '\.(cpp|h|cu|cuh)$' | xargs clang-format-18 -i
+             git ls-files | grep -E  '\.(cpp|h|cu|cuh)$' | xargs clang-format -i
              if git diff --quiet; then
                echo "Formatting OK!"
              else
diff --git a/.circleci/setup-clang-format.sh b/.circleci/setup-clang-format.sh
new file mode 100755
index 0000000000..a94691f9e1
--- /dev/null
+++ b/.circleci/setup-clang-format.sh
@@ -0,0 +1,43 @@
+#!/bin/bash
+# (c) Meta Platforms, Inc. and affiliates. Confidential and proprietary.
+
+set -euo pipefail
+# https://reproducible-builds.org/docs/archives/
+deterministic_tar_gz() {
+  # Use year 2030 to thwart tmpreaper.
+  tar \
+    --sort=name \
+    --mtime=2030-01-01T00:00:00Z \
+    --owner=0 --group=0 --numeric-owner \
+    -cf- \
+    "${@:2}" \
+  | gzip -9n \
+  > "$1"
+}
+
+# To curl from devservers
+if host -W 1 fwdproxy >/dev/null; then
+  curl() { HTTP_PROXY=fwdproxy:8080 HTTPS_PROXY=fwdproxy:8080 command curl "$@"; }
+fi
+
+### CHANGE THESE VARIABLES WHEN UPDATING ###
+
+# https://pypi.org/project/clang-format/18.1.3
+
+
+LINUX_X86_64_URL=https://files.pythonhosted.org/packages/d5/9c/4f3806d20397790b3cd80aef89d295bf399581804f5c5758b6207e54e902/clang_format-18.1.3-py2.py3-none-manylinux_2_17_x86_64.manylinux2014_x86_64.whl
+
+###
+NAME=${LINUX_X86_64_URL##*/}
+
+set -x
+curl -L -o "$NAME.zip" "$LINUX_X86_64_URL"
+mkdir "clang-format"
+unzip -q -d "clang-format" "$NAME.zip"
+echo "clang-format/clang_format/data/bin"
+deterministic_tar_gz "$NAME.tar.gz" -C "clang-format/clang_format/data/bin" "clang-format"
+tar tvf "$NAME.tar.gz"
+
+echo "$PWD"
+export PATH="${PWD}/clang-format/clang_format/data/bin:$PATH"
+echo $PATH
diff --git a/faiss/impl/NNDescent.cpp b/faiss/impl/NNDescent.cpp
index b609aba390..5afcdaf5b7 100644
--- a/faiss/impl/NNDescent.cpp
+++ b/faiss/impl/NNDescent.cpp
@@ -154,15 +154,20 @@ NNDescent::NNDescent(const int d, const int K) : K(K), d(d) {
 NNDescent::~NNDescent() {}
 
 void NNDescent::join(DistanceComputer& qdis) {
+    idx_t check_period = InterruptCallback::get_period_hint(d * search_L);
+    for (idx_t i0 = 0; i0 < (idx_t)ntotal; i0 += check_period) {
+        idx_t i1 = std::min(i0 + check_period, (idx_t)ntotal);
 #pragma omp parallel for default(shared) schedule(dynamic, 100)
-    for (int n = 0; n < ntotal; n++) {
-        graph[n].join([&](int i, int j) {
-            if (i != j) {
-                float dist = qdis.symmetric_dis(i, j);
-                graph[i].insert(j, dist);
-                graph[j].insert(i, dist);
-            }
-        });
+        for (idx_t n = i0; n < i1; n++) {
+            graph[n].join([&](int i, int j) {
+                if (i != j) {
+                    float dist = qdis.symmetric_dis(i, j);
+                    graph[i].insert(j, dist);
+                    graph[j].insert(i, dist);
+                }
+            });
+        }
+        InterruptCallback::check();
     }
 }