diff --git a/scripts/kernel-functions b/scripts/kernel-functions
index da0d1fd93..cbceca70c 100644
--- a/scripts/kernel-functions
+++ b/scripts/kernel-functions
@@ -39,16 +39,46 @@ function check_kernel_version {
   fi
 }
 
-# Download the file from URL $1 and save it in the current directory.
+# Verify that a downloaded file is nonempty and, based on $2 or its own name,
+# that XZ data is intact.
+function download_is_readable {
+  local filename="${2:-$1}"
+
+  [ -s "$1" ] || return 1
+  case "$filename" in
+    *.xz) xz -t "$1" >/dev/null 2>&1;;
+  esac
+}
+
+# Download the file from URL $1 and save it atomically in the current
+# directory.
 function download_file {
-  if [ ! -e "$(basename "$1")" ]; then
-    if [ "${quiet_download}" = "false" ]; then
-      { wget -q -nc -O- "$1" 2>/dev/null | grep -q .; } \
-        && echo "Downloading $1 ..."
+  local filename tmpfile
+
+  filename="$(basename "$1")"
+
+  if [ -e "$filename" ]; then
+    if download_is_readable "$filename"; then
+      return 0
     fi
-    wget -q -nc "$1"
+    echo "Removing invalid cached download $filename." >&2
+    rm -f "$filename" || return $?
+  fi
+
+  if [ "${quiet_download}" = "false" ]; then
+    echo "Downloading $1 ..."
+  fi
+  tmpfile="$(mktemp "${filename}.tmp.XXXXXX")" || return $?
+  if ! wget -q -O "$tmpfile" "$1" ||
+     ! download_is_readable "$tmpfile" "$filename"; then
+    echo "Error: download $1 is incomplete or invalid." >&2
+    rm -f "$tmpfile"
+    return 1
+  fi
+  if ! mv "$tmpfile" "$filename"; then
+    rm -f "$tmpfile"
+    return 1
   fi
-  [ -e "$(basename "$1")" ]
 }
 
 # Make sure the kernel tarball and patch file are present in directory
@@ -83,9 +113,13 @@ function extract_kernel_archive {
   local series="$1"
 
   if [ -e "${kernel_downloads}/linux-$1.tar.xz" ]; then
-    xz -cd "${kernel_downloads}/linux-$1.tar.xz" | tar xf -
+    ( set -o pipefail
+      xz -cd "${kernel_downloads}/linux-$1.tar.xz" | tar xf -
+    )
   elif [ -e "${kernel_downloads}/linux-$kver.tar.xz" ]; then
-    xz -cd "${kernel_downloads}/linux-$kver.tar.xz" | tar xf - &&
+    ( set -o pipefail
+      xz -cd "${kernel_downloads}/linux-$kver.tar.xz" | tar xf -
+    ) &&
       mv "linux-$kver" "linux-$1"
   elif [ -e "${kernel_downloads}/linux-$1.tar.bz2" ]; then
     tar xjf "${kernel_downloads}/linux-$1.tar.bz2"
@@ -112,8 +146,10 @@ function extract_kernel_tree {
        [ -e "${kernel_downloads}/patch-$1.xz" ]; then
       extract_kernel_archive "$kver" || return $?
       mv "linux-$kver" "linux-$1"
-      ( cd "linux-$1" && xz -cd "${kernel_downloads}/patch-$1.xz" \
-        | patch -p1 -f -s; ) \
+      ( set -o pipefail
+        cd "linux-$1" && xz -cd "${kernel_downloads}/patch-$1.xz" \
+          | patch -p1 -f -s
+      ) \
         || return $?
     else
 	extract_kernel_archive "$1" ||
diff --git a/scripts/run-regression-tests b/scripts/run-regression-tests
index f16ab18ba..4a93159a4 100755
--- a/scripts/run-regression-tests
+++ b/scripts/run-regression-tests
@@ -564,8 +564,8 @@ scriptsdir="$(dirname "$0")"
 if [ "${scriptsdir:0:1}" != "/" ]; then
   scriptsdir="$PWD/${scriptsdir}"
 fi
-# Where to store persistenly downloaded kernel tarballs and kernel patches.
-kernel_sources="$HOME/software/downloads"
+# Where to store persistently downloaded kernel tarballs and kernel patches.
+kernel_downloads="$HOME/software/downloads"
 kernel_versions=""
 # Directory in which the regression test output files will be stored. Must be
 # an absolute path.
@@ -583,7 +583,7 @@ quiet_download="false"
 while [ "$1" != "${1#-}" ]
 do
   case "$1" in
-    '-c') kernel_sources="$2"; shift; shift;;
+    '-c') kernel_downloads="$2"; shift; shift;;
     '-d') outputdir="$2"; shift; shift;;
     '-h') usage; exit 1;;
     '-j') export MAKEFLAGS="-j$2"; shift; shift;;