diff --git a/bin/on-all-blogs b/bin/on-all-blogs
index 15240b5bda1c58fc4acbbd00849d23d80050eade..32cee2f8182c3f633128fa4dec67709d95ac0518 100755
--- a/bin/on-all-blogs
+++ b/bin/on-all-blogs
@@ -1,4 +1,4 @@
-#!/bin/bash
+#!/bin/sh
 #
 # Run a 'noblogs' command on all blogs.
 #
diff --git a/bin/on-local-blogs b/bin/on-local-blogs
index ece05aea6a2d4073db14feaf69d7d1086afe1617..af478f8e7aebba166661367049c8e7c5c468019f 100755
--- a/bin/on-local-blogs
+++ b/bin/on-local-blogs
@@ -1,4 +1,4 @@
-#!/bin/bash
+#!/bin/sh
 #
 # Run a 'noblogs' command on just those blogs that are hosted
 # on this server.
@@ -16,5 +16,4 @@ dir=${dir:-.}
 abs_dir=$(cd ${dir} && pwd)
 
 ${dir}/noblogs print-local-blogs | grep -v Warning \
-    | xargs -n 30 ${abs_dir}/noblogs "$@"
-
+    | xargs -n ${CONCURRENCY:-30} ${abs_dir}/noblogs "$@"