diff --git a/pbc b/pbc
index 30be180..3e939fd 100755
--- a/pbc
+++ b/pbc
@@ -197,7 +197,7 @@ SCRIPT_PATH=$(realpath -s "$0")
 SCRIPT_DIR=$(dirname "$SCRIPT_PATH")
 SCRIPT=$(basename "$SCRIPT_PATH")
 
-PBC=$(which proxmox-backup-client)
+PBC=$(command -v proxmox-backup-client)
 PBC_DOWNLOAD_URL='http://download.proxmox.com/debian/pbs-client/dists/trixie/main/binary-amd64'
 ETC_DIR="/etc/$SCRIPT"
 
@@ -263,14 +263,14 @@ if [ "$action" == 'install' ]; then
   fi
   PBC=${PBC:-/usr/local/bin/proxmox-backup-client}
   for exe in apt-get dpkg dpkg-deb curl; do
-    ! which -s "$exe" && echo "Error: $exe executable not found!" >&2 && exit 200
+    ! command -v "$exe" >/dev/null && echo "Error: $exe executable not found!" >&2 && exit 200
   done
 else
   source "$cfgfile" || exit $?
   PBC=${PBC:-/usr/local/bin/proxmox-backup-client}
   [ ! -f "$PBC" ] && echo "Error: $PBC: no such file" >&2 && exit 200
   [ ! -e "$PBC" ] && echo "Error: $PBC: not executable" >&2 && exit 200
-  ! which -s jq && echo "Error: jq executable not found!" >&2 && exit 200
+  ! command -v jq >/dev/null && echo "Error: jq executable not found!" >&2 && exit 200
 fi
 
 export PBS_REPOSITORY="$PBS_USER@$PBS_SERVER:$PBS_DATASTORE"