diff --git a/CTestCustom.cmake.in b/CTestCustom.cmake.in
new file mode 100644
index 0000000000..c437205608
--- /dev/null
+++ b/CTestCustom.cmake.in
@@ -0,0 +1,21 @@
+# Copyright 1993, 1994, 1995, 1996, 1997, 1998, 1999, 2000, 2001, 2002,
+# 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010, 2011, 2012, 2013, 2014,
+# 2015, 2016, 2017, 2018
+# University Corporation for Atmospheric Research/Unidata.
+
+# See netcdf-c/COPYRIGHT file for more info.
+## This file is used to customize CTest.
+## See:
+##
+##  http://public.kitware.com/Wiki/CTest:Using_CTEST_and_CDASH_without_CMAKE
+##
+## for more information.
+
+set(CTEST_CUSTOM_MAXIMUM_NUMBER_OF_WARNINGS "500")
+
+IF(ENABLE_S3_TESTING)
+# Before and after all tests are run, we need to try to cleanup the junk left in the Unidata S3 bucket.
+# Assume run in top-level CMAKE_BINARY_DIR
+set(CTEST_CUSTOM_PRE_TEST "${CMAKE_BINARY_DIR}/nczarr_test/run_s3_cleanup.sh ${CMAKE_BINARY_DIR} ${S3TESTSUBTREE}")
+set(CTEST_CUSTOM_POST_TEST "${CMAKE_BINARY_DIR}/nczarr_test/run_s3_cleanup.sh ${CMAKE_BINARY_DIR} ${S3TESTSUBTREE}")
+ENDIF()
diff --git a/nc_test4/tst_filter_misc.sh b/nc_test4/tst_filter_misc.sh
index 7e8ad8bef8..4efe553613 100755
--- a/nc_test4/tst_filter_misc.sh
+++ b/nc_test4/tst_filter_misc.sh
@@ -21,6 +21,14 @@ if test "x$TESTNCZARR" = x1; then
 s3isolate
 fi
 
+if test "x$TESTNCZARR" = x1; then
+    TFAVAIL =${execdir}/test_filter_avail
+    TFVLEN =${execdir}/test_filter_vlen
+else
+    TFAVAIL =${execdir}/tst_filter_avail
+    TFVLEN =${execdir}/tst_filter_vlen
+fi
+
 # Load the findplugins function
 . ${builddir}/findplugin.sh
 echo "findplugin.sh loaded"
@@ -85,20 +93,12 @@ setfilter() {
 testavail() {
   zext=$1
   if ! filteravail bzip2; then return 0; fi
-  if test "x$TESTNCZARR" = x1 ; then
-      ${execdir}/test_filter_avail
-  else
-      ${execdir}/tst_filter_avail
-  fi
+  ${TFAVAIL}
 }
 
 testvlen() {
   zext=$1
-  if test "x$TESTNCZARR" = x1 ; then
-      ${execdir}/test_filter_vlen
-  else
-      ${execdir}/tst_filter_vlen
-  fi
+  ${TFVLEN}
 }
 
 testset() {
diff --git a/nczarr_test/run_s3_cleanup.sh b/nczarr_test/run_s3_cleanup.sh
index 542af09d5c..0a593c0876 100755
--- a/nczarr_test/run_s3_cleanup.sh
+++ b/nczarr_test/run_s3_cleanup.sh
@@ -1,19 +1,9 @@
 #!/bin/sh
 
-if test "x$srcdir" = x ; then srcdir=`pwd`; fi 
-. ../test_common.sh
-
-. "$srcdir/test_nczarr.sh"
-
-set -e
-
-echo ""
-echo "*** Remove /netcdf-c from S3 repository"
-
-fileargs netcdf-c
-
-if test "x$FEATURE_S3TESTS" = xyes ; then
-${execdir}/s3util -u "${NCZARR_S3_TEST_URL}" -k "/netcdf-c" clear
-fi
+set -x
+TESTDIR="$1"
+S3TESTSUBTREE="$2"
 
+echo ">>> *** Remove /${TESTSUBTREE} from S3 repository"
+echo ${TESTDIR}/nczarr_test/s3util -u "https://s3.us-east-1.amazonaws.com/unidata-zarr-test-data" -k "/${S3TESTSUBTREE}" clear
 exit 0