diff --git a/mcrouter/scripts/common.sh b/mcrouter/scripts/common.sh
index c2ad444a1..214325f71 100644
--- a/mcrouter/scripts/common.sh
+++ b/mcrouter/scripts/common.sh
@@ -14,7 +14,7 @@ PKG_DIR="$1"
 INSTALL_DIR="$2"
 INSTALL_AUX_DIR="$3"
 shift $#
-MAKE_ARGS="$@ -j4"
+MAKE_ARGS="$@ -j$(nproc)"
 SCRIPT_DIR="$(cd "$(dirname "$0")" && pwd)"
 
 mkdir -p "$PKG_DIR" "$INSTALL_DIR"
diff --git a/mcrouter/scripts/docker/ubuntu/Dockerfile-20.04 b/mcrouter/scripts/docker/ubuntu/Dockerfile-20.04
index 628b45ed7..3c1d73115 100644
--- a/mcrouter/scripts/docker/ubuntu/Dockerfile-20.04
+++ b/mcrouter/scripts/docker/ubuntu/Dockerfile-20.04
@@ -1,4 +1,4 @@
-# syntax=docker/dockerfile:1.1-experimental
+# syntax=docker/dockerfile:1.3
 FROM ubuntu:20.04 as build
 
 ENV DEBIAN_FRONTEND noninteractive
diff --git a/mcrouter/scripts/recipes/fbthrift.sh b/mcrouter/scripts/recipes/fbthrift.sh
index ee31c38eb..a4e84bef8 100755
--- a/mcrouter/scripts/recipes/fbthrift.sh
+++ b/mcrouter/scripts/recipes/fbthrift.sh
@@ -7,7 +7,7 @@
 source common.sh
 
 if [[ ! -d "$PKG_DIR/fbthrift" ]]; then
-  git clone -b main https://github.com/facebook/fbthrift
+  git clone https://github.com/facebook/fbthrift
   cd "$PKG_DIR/fbthrift" || die "cd fail"
   if [[ -f "$REPO_BASE_DIR/mcrouter/FBTHRIFT_COMMIT" ]]; then
     FBTHRIFT_COMMIT="$(head -n 1 "$REPO_BASE_DIR/mcrouter/FBTHRIFT_COMMIT")"