diff --git a/utils/checkcert.sh b/utils/checkcert.sh
index 5905562..24a27f5 100755
--- a/utils/checkcert.sh
+++ b/utils/checkcert.sh
@@ -74,7 +74,7 @@ datebanner() {
 
 dns() {
 	ip4=`host -t a $1 | grep -v alias | sed 's/^.*address //'`
-	which getent 2>&1 >/dev/null && getent ahostsv4 $1 2>&1 >/dev/null && ip4=`getent ahostsv4 $1 | awk '{ print $1}' | uniq`
+	command -v getent 2>&1 >/dev/null && getent ahostsv4 $1 2>&1 >/dev/null && ip4=`getent ahostsv4 $1 | awk '{ print $1}' | uniq`
 	NODEIP=`echo "$ip4" | head -1`
 	rDNS=`host -t PTR $NODEIP | sed -e 's/^.*pointer //' -e 's/\.$//'`
 	echo $rDNS | grep -q NXDOMAIN  && rDNS=""
diff --git a/utils/curves.bash b/utils/curves.bash
index 8a8f76b..2a00f63 100755
--- a/utils/curves.bash
+++ b/utils/curves.bash
@@ -36,7 +36,7 @@ find_openssl_binary() {
           :    # 2. otherwise try openssl in path of testssl.sh
      elif test_openssl_suffix ../$RUN_DIR/bin; then
           :    # 3. otherwise here, this is supposed to be the standard --platform independent path in the future!!!
-     elif test_openssl_suffix "$(dirname "$(which openssl)")"; then
+     elif test_openssl_suffix "$(dirname "$(command -v openssl)")"; then
           :    # 5. we tried hard and failed, so now we use the system binaries
      fi
 
diff --git a/utils/generate_static_cipher_lists.sh b/utils/generate_static_cipher_lists.sh
index 6e4a8e8..85d747c 100755
--- a/utils/generate_static_cipher_lists.sh
+++ b/utils/generate_static_cipher_lists.sh
@@ -67,7 +67,7 @@ get_mapping_file() {
      fi
 
      # we haven't found the cipher file yet...
-     if [[ ! -r "$CIPHERS_BY_STRENGTH_FILE" ]] && which readlink &>/dev/null ; then
+     if [[ ! -r "$CIPHERS_BY_STRENGTH_FILE" ]] && command -v readlink &>/dev/null ; then
           readlink -f ls &>/dev/null && \
                TESTSSL_INSTALL_DIR=$(readlink -f $(basename ${BASH_SOURCE[0]})) || \
                TESTSSL_INSTALL_DIR=$(readlink $(basename ${BASH_SOURCE[0]}))
@@ -78,14 +78,14 @@ get_mapping_file() {
      fi
 
      # still no cipher mapping file:
-     if [[ ! -r "$CIPHERS_BY_STRENGTH_FILE" ]] && which realpath &>/dev/null ; then
+     if [[ ! -r "$CIPHERS_BY_STRENGTH_FILE" ]] && command -v realpath &>/dev/null ; then
           TESTSSL_INSTALL_DIR=$(dirname $(realpath ${BASH_SOURCE[0]}))
           CIPHERS_BY_STRENGTH_FILE="$TESTSSL_INSTALL_DIR/etc/cipher-mapping.txt"
           [[ -r "$TESTSSL_INSTALL_DIR/cipher-mapping.txt" ]] && CIPHERS_BY_STRENGTH_FILE="$TESTSSL_INSTALL_DIR/cipher-mapping.txt"
      fi
 
      # still no cipher mapping file (and realpath is not present):
-     if [[ ! -r "$CIPHERS_BY_STRENGTH_FILE" ]] && which readlink &>/dev/null ; then
+     if [[ ! -r "$CIPHERS_BY_STRENGTH_FILE" ]] && command -v readlink &>/dev/null ; then
          readlink -f ls &>/dev/null && \
               TESTSSL_INSTALL_DIR=$(dirname $(readlink -f ${BASH_SOURCE[0]})) || \
               TESTSSL_INSTALL_DIR=$(dirname $(readlink ${BASH_SOURCE[0]}))