diff --git a/amd64/additional-base-lib/build.sh b/amd64/additional-base-lib/build.sh
index 66a2f1c..dc36e20 100755
--- a/amd64/additional-base-lib/build.sh
+++ b/amd64/additional-base-lib/build.sh
@@ -82,7 +82,7 @@ pushd $WORKDIR
 
 LIBC6_DOWNLOAD_URL=$(curl -s https://packages.debian.org/sid/${ARCH}/libc6/download | grep -o "http://ftp.cn.debian.org/debian/pool/main/g/glibc/libc6_.*_${ARCH}.deb")
 LIBC_BIN_DOWNLOAD_URL=$(curl -s https://packages.debian.org/sid/${ARCH}/libc-bin/download | grep -o "http://ftp.cn.debian.org/debian/pool/main/g/glibc/libc-bin_.*_${ARCH}.deb")
-LIBSTDCxx6_DOWNLOAD_URL=curl -s https://packages.debian.org/sid/${ARCH}/libstdc++6/download | grep -o "http://ftp.cn.debian.org/debian/.*_${ARCH}.deb"
+LIBSTDCxx6_DOWNLOAD_URL=$(curl -s https://packages.debian.org/sid/${ARCH}/libstdc++6/download | grep -o "http://ftp.cn.debian.org/debian/.*_${ARCH}.deb")
 
 ABL_VERSION=9