diff --git a/build b/build
index ad39910..05b3abc 100755
--- a/build
+++ b/build
@@ -145,8 +145,12 @@ cpus="$(command getconf _NPROCESSORS_ONLN 2>/dev/null)" ||
   cpus=8
 
 case "$gitstatus_cpu" in
-  powerpc64le) archflag="-mcpu";;
-  *)           archflag="-march";;
+  powerpc64|powerpc64le)
+    archflag="-mcpu"
+  ;;
+  *)
+    archflag="-march"
+  ;;
 esac
 
 cflags="$archflag=$gitstatus_cpu -fno-plt -D_FORTIFY_SOURCE=2 -Wformat -Werror=format-security -fpie"
@@ -520,7 +524,7 @@ if [ -z "$gitstatus_cpu" ]; then
     armv6l|armhf)   gitstatus_cpu=armv6;;
     armv7l)         gitstatus_cpu=armv7;;
     arm64|aarch64)  gitstatus_cpu=armv8-a;;
-    ppc64le)        gitstatus_cpu=powerpc64le;;
+    ppc64|ppc64le)  gitstatus_cpu=powerpc64le;;
     riscv64)        gitstatus_cpu=rv64imafdc;;
     loongarch64)    gitstatus_cpu=loongarch64;;
     x86_64|amd64)   gitstatus_cpu=x86-64;;
@@ -559,7 +563,7 @@ case "$gitstatus_kernel" in
           armv6l|armhf)       docker_image=arm32v6/alpine:3.11.6;;
           armv7l)             docker_image=arm32v7/alpine:3.11.6;;
           aarch64)            docker_image=arm64v8/alpine:3.11.6;;
-          ppc64le)            docker_image=ppc64le/alpine:3.11.6;;
+          ppc64|ppc64le)      docker_image=ppc64le/alpine:3.11.6;;
           s390x)              docker_image=s390x/alpine:3.11.6;;
           *)
             >&2 echo '[error] unable to infer docker image'
diff --git a/gitstatus.plugin.sh b/gitstatus.plugin.sh
index 0c66096..37b78f4 100644
--- a/gitstatus.plugin.sh
+++ b/gitstatus.plugin.sh
@@ -121,7 +121,12 @@ function gitstatus_start() {
       --repo-ttl-seconds="$ttl"
       $extra_flags)
 
-    tmpdir="$(command mktemp -d "${TMPDIR:-/tmp}"/gitstatus.bash.$$.XXXXXXXXXX)" || return
+    if [[ -n "$TMPDIR" && ( ( -d "$TMPDIR" && -w "$TMPDIR" ) || ! ( -d /tmp && -w /tmp ) ) ]]; then
+      local tmpdir=$TMPDIR
+    else
+      local tmpdir=/tmp
+    fi
+    tmpdir="$(command mktemp -d "$tmpdir"/gitstatus.bash.$$.XXXXXXXXXX)" || return
 
     if [[ -n "$log_level" ]]; then
       GITSTATUS_DAEMON_LOG="$tmpdir"/daemon.log
diff --git a/gitstatus.plugin.zsh b/gitstatus.plugin.zsh
index 181e756..228fea7 100644
--- a/gitstatus.plugin.zsh
+++ b/gitstatus.plugin.zsh
@@ -574,7 +574,12 @@ function gitstatus_start"${1:-}"() {
     else
       typeset -gi _GITSTATUS_START_COUNTER
       local log_level=$GITSTATUS_LOG_LEVEL
-      local file_prefix=${${TMPDIR:-/tmp}:A}/gitstatus.$name.$EUID
+      if [[ -n "$TMPDIR" && ( ( -d "$TMPDIR" && -w "$TMPDIR" ) || ! ( -d /tmp && -w /tmp ) ) ]]; then
+        local tmpdir=$TMPDIR
+      else
+        local tmpdir=/tmp
+      fi
+      local file_prefix=${tmpdir:A}/gitstatus.$name.$EUID
       file_prefix+=.$sysparams[pid].$EPOCHSECONDS.$((++_GITSTATUS_START_COUNTER))
       (( GITSTATUS_ENABLE_LOGGING )) && : ${log_level:=INFO}
       if [[ -n $log_level ]]; then
diff --git a/install b/install
index a0142b2..6e027a3 100755
--- a/install
+++ b/install
@@ -245,27 +245,30 @@ END
       return 1
     fi
 
-    local tmpdir
+    if [ -n "$TMPDIR" -a '(' '(' -d "$TMPDIR" -a -w "$TMPDIR" ')' -o '!' '(' -d /tmp -a -w /tmp ')' ')' ]; then
+      local tmp="$TMPDIR"
+    else
+      local tmp=/tmp
+    fi
     if ! command -v mktemp >/dev/null 2>&1 ||
-       ! tmpdir="$(command mktemp -d "${TMPDIR:-/tmp}"/gitstatus-install.XXXXXXXXXX)"; then
-      tmpdir="${TMPDIR:-/tmp}/gitstatus-install.tmp.$$"
+       ! tmpdir="$(command mktemp -d "$tmp"/gitstatus-install.XXXXXXXXXX)"; then
+      tmpdir="$tmp/gitstatus-install.tmp.$$"
       if ! mkdir -p -- "$tmpdir"; then
-        local dir="${TMPDIR:-/tmp}"
-        if [ -z "${TMPDIR:-}" ]; then
+        if [ "$tmp" = /tmp ]; then
           local label='directory'
         else
           local label='directory (\033[1mTMPDIR\033[m)'
         fi
-        if [ ! -e "$dir" ]; then
-          >&"$e" printf 'Temporary '"$label"' does not exist: \033[4;31m%s\033[0m\n' "$dir"
+        if [ ! -e "$tmp" ]; then
+          >&"$e" printf 'Temporary '"$label"' does not exist: \033[4;31m%s\033[0m\n' "$tmp"
           >&"$e" printf '\n'
           >&"$e" printf 'Create it, then restart your shell.\n'
-        elif [ ! -d "$dir" ]; then
-          >&"$e" printf 'Not a '"$label"': \033[4;31m%s\033[0m\n' "$dir"
+        elif [ ! -d "$tmp" ]; then
+          >&"$e" printf 'Not a '"$label"': \033[4;31m%s\033[0m\n' "$tmp"
           >&"$e" printf '\n'
           >&"$e" printf 'Make it a directory, then restart your shell.\n'
-        elif [ ! -w "$dir" ]; then
-          >&"$e" printf 'Temporary '"$label"' is not writable: \033[4;31m%s\033[0m\n' "$dir"
+        elif [ ! -w "$tmp" ]; then
+          >&"$e" printf 'Temporary '"$label"' is not writable: \033[4;31m%s\033[0m\n' "$tmp"
           >&"$e" printf '\n'
           >&"$e" printf 'Make it writable, then restart your shell.\n'
         fi