diff --git a/tests/compat-in-docker.sh b/tests/compat-in-docker.sh
index 6b3cd2d..090c6ce 100755
--- a/tests/compat-in-docker.sh
+++ b/tests/compat-in-docker.sh
@@ -12,7 +12,7 @@
 #
 # Notes for users
 # ---------------
-# If OPENSSL_CMD, GNUTLS_CLI, or GNUTLS_SERV are specified the path must
+# If OPENSSL, GNUTLS_CLI, or GNUTLS_SERV are specified the path must
 # correspond to an executable inside the Docker container. The special
 # values "next" (OpenSSL only) and "legacy" are also allowed as shorthand
 # for the installations inside the container.
@@ -38,9 +38,9 @@
 
 source tests/scripts/docker_env.sh
 
-case "${OPENSSL_CMD:-default}" in
-    "legacy")  export OPENSSL_CMD="/usr/local/openssl-1.0.1j/bin/openssl";;
-    "next")    export OPENSSL_CMD="/usr/local/openssl-1.1.1a/bin/openssl";;
+case "${OPENSSL:-default}" in
+    "legacy")  export OPENSSL="/usr/local/openssl-1.0.1j/bin/openssl";;
+    "next")    export OPENSSL="/usr/local/openssl-1.1.1a/bin/openssl";;
     *) ;;
 esac
 
@@ -61,7 +61,7 @@
     -e M_SRV \
     -e GNUTLS_CLI \
     -e GNUTLS_SERV \
-    -e OPENSSL_CMD \
+    -e OPENSSL \
     -e OSSL_NO_DTLS \
     tests/compat.sh \
     $@
diff --git a/tests/compat.sh b/tests/compat.sh
index 6791c55..c06694e 100755
--- a/tests/compat.sh
+++ b/tests/compat.sh
@@ -39,10 +39,21 @@
 # default commands, can be overridden by the environment
 : ${M_SRV:=../programs/ssl/ssl_server2}
 : ${M_CLI:=../programs/ssl/ssl_client2}
-: ${OPENSSL_CMD:=openssl} # OPENSSL would conflict with the build system
+: ${OPENSSL:=openssl}
 : ${GNUTLS_CLI:=gnutls-cli}
 : ${GNUTLS_SERV:=gnutls-serv}
 
+# The OPENSSL variable used to be OPENSSL_CMD for historical reasons.
+# To help the migration, error out if the old variable is set,
+# but only if it has a different value than the new one.
+if [ "${OPENSSL_CMD+set}" = set ]; then
+    # the variable is set, we can now check its value
+    if [ "$OPENSSL_CMD" != "$OPENSSL" ]; then
+        echo "Please use OPENSSL instead of OPENSSL_CMD." >&2
+        exit 125
+    fi
+fi
+
 # do we have a recent enough GnuTLS?
 if ( which $GNUTLS_CLI && which $GNUTLS_SERV ) >/dev/null 2>&1; then
     G_VER="$( $GNUTLS_CLI --version | head -n1 )"
@@ -916,7 +927,7 @@
     # Mbed TLS wants >=1024, so force that for older versions. Don't force
     # it for newer versions, which reject a 1024-bit prime. Indifferently
     # force it or not for intermediate versions.
-    case $($OPENSSL_CMD version) in
+    case $($OPENSSL version) in
         "OpenSSL 1.0"*)
             O_SERVER_ARGS="$O_SERVER_ARGS -dhparam data_files/dhparams.pem"
             ;;
@@ -940,7 +951,7 @@
     # OpenSSL 1.1.1f from Ubuntu 20.04. The syntax was only introduced in
     # OpenSSL 1.1.0 (21e0c1d23afff48601eb93135defddae51f7e2e3) and I can't find
     # a way to discover it from -help, so check the openssl version.
-    case $($OPENSSL_CMD version) in
+    case $($OPENSSL version) in
         "OpenSSL 0"*|"OpenSSL 1.0"*) :;;
         *)
             O_CLIENT_ARGS="$O_CLIENT_ARGS -cipher ALL@SECLEVEL=0"
@@ -1059,7 +1070,7 @@
 start_server() {
     case $1 in
         [Oo]pen*)
-            SERVER_CMD="$OPENSSL_CMD s_server $O_SERVER_ARGS"
+            SERVER_CMD="$OPENSSL s_server $O_SERVER_ARGS"
             ;;
         [Gg]nu*)
             SERVER_CMD="$GNUTLS_SERV $G_SERVER_ARGS --priority $G_SERVER_PRIO"
@@ -1149,7 +1160,7 @@
     # run the command and interpret result
     case $1 in
         [Oo]pen*)
-            CLIENT_CMD="$OPENSSL_CMD s_client $O_CLIENT_ARGS -cipher $2"
+            CLIENT_CMD="$OPENSSL s_client $O_CLIENT_ARGS -cipher $2"
             log "$CLIENT_CMD"
             echo "$CLIENT_CMD" > $CLI_OUT
             printf 'GET HTTP/1.0\r\n\r\n' | $CLIENT_CMD >> $CLI_OUT 2>&1 &
@@ -1284,8 +1295,8 @@
 fi
 
 if echo "$PEERS" | grep -i openssl > /dev/null; then
-    if which "$OPENSSL_CMD" >/dev/null 2>&1; then :; else
-        echo "Command '$OPENSSL_CMD' not found" >&2
+    if which "$OPENSSL" >/dev/null 2>&1; then :; else
+        echo "Command '$OPENSSL' not found" >&2
         exit 1
     fi
 fi
@@ -1348,7 +1359,7 @@
                     # help isn't accurate as of 1.0.2g: it supports DTLS 1.2
                     # but doesn't list it. But the s_server help seems to be
                     # accurate.)
-                    if ! $OPENSSL_CMD s_server -help 2>&1 | grep -q "^ *-$O_MODE "; then
+                    if ! $OPENSSL s_server -help 2>&1 | grep -q "^ *-$O_MODE "; then
                         continue;
                     fi
 
diff --git a/tests/scripts/all.sh b/tests/scripts/all.sh
index 1a2b10a..061ec8b 100755
--- a/tests/scripts/all.sh
+++ b/tests/scripts/all.sh
@@ -713,7 +713,7 @@
         *" test_"*)
             # To avoid setting OpenSSL and GnuTLS for each call to compat.sh
             # and ssl-opt.sh, we just export the variables they require.
-            export OPENSSL_CMD="$OPENSSL"
+            export OPENSSL="$OPENSSL"
             export GNUTLS_CLI="$GNUTLS_CLI"
             export GNUTLS_SERV="$GNUTLS_SERV"
             # Avoid passing --seed flag in every call to ssl-opt.sh
@@ -1018,7 +1018,7 @@
 
     msg "build: SSLv3 - compat.sh (ASan build)" # ~ 6 min
     tests/compat.sh -m 'tls1 tls1_1 tls12 dtls1 dtls12'
-    env OPENSSL_CMD="$OPENSSL_LEGACY" tests/compat.sh -m 'ssl3'
+    env OPENSSL="$OPENSSL_LEGACY" tests/compat.sh -m 'ssl3'
 
     msg "build: SSLv3 - ssl-opt.sh (ASan build)" # ~ 6 min
     tests/ssl-opt.sh
@@ -1550,10 +1550,10 @@
     tests/ssl-opt.sh -f 'Default\|ECJPAKE\|SSL async private'
 
     msg "test: compat.sh RC4, DES, 3DES & NULL (full config)" # ~ 2 min
-    env OPENSSL_CMD="$OPENSSL_LEGACY" GNUTLS_CLI="$GNUTLS_LEGACY_CLI" GNUTLS_SERV="$GNUTLS_LEGACY_SERV" tests/compat.sh -e '^$' -f 'NULL\|DES\|RC4\|ARCFOUR'
+    env OPENSSL="$OPENSSL_LEGACY" GNUTLS_CLI="$GNUTLS_LEGACY_CLI" GNUTLS_SERV="$GNUTLS_LEGACY_SERV" tests/compat.sh -e '^$' -f 'NULL\|DES\|RC4\|ARCFOUR'
 
     msg "test: compat.sh ARIA + ChachaPoly"
-    env OPENSSL_CMD="$OPENSSL_NEXT" tests/compat.sh -e '^$' -f 'ARIA\|CHACHA'
+    env OPENSSL="$OPENSSL_NEXT" tests/compat.sh -e '^$' -f 'ARIA\|CHACHA'
 }
 
 skip_suites_without_constant_flow () {
@@ -1829,10 +1829,10 @@
     tests/compat.sh
 
     msg "test: compat.sh RC4, DES & NULL (full minus MBEDTLS_USE_PSA_CRYPTO)"
-    env OPENSSL_CMD="$OPENSSL_LEGACY" GNUTLS_CLI="$GNUTLS_LEGACY_CLI" GNUTLS_SERV="$GNUTLS_LEGACY_SERV" tests/compat.sh -e '3DES\|DES-CBC3' -f 'NULL\|DES\|RC4\|ARCFOUR'
+    env OPENSSL="$OPENSSL_LEGACY" GNUTLS_CLI="$GNUTLS_LEGACY_CLI" GNUTLS_SERV="$GNUTLS_LEGACY_SERV" tests/compat.sh -e '3DES\|DES-CBC3' -f 'NULL\|DES\|RC4\|ARCFOUR'
 
     msg "test: compat.sh ARIA + ChachaPoly (full minus MBEDTLS_USE_PSA_CRYPTO)"
-    env OPENSSL_CMD="$OPENSSL_NEXT" tests/compat.sh -e '^$' -f 'ARIA\|CHACHA'
+    env OPENSSL="$OPENSSL_NEXT" tests/compat.sh -e '^$' -f 'ARIA\|CHACHA'
 }
 
 component_test_psa_crypto_config_accel_ecdsa () {
diff --git a/tests/scripts/basic-build-test.sh b/tests/scripts/basic-build-test.sh
index 7c0fe5a..abc4a2f 100755
--- a/tests/scripts/basic-build-test.sh
+++ b/tests/scripts/basic-build-test.sh
@@ -69,7 +69,7 @@
 
 # To avoid setting OpenSSL and GnuTLS for each call to compat.sh and ssl-opt.sh
 # we just export the variables they require
-export OPENSSL_CMD="$OPENSSL"
+export OPENSSL="$OPENSSL"
 export GNUTLS_CLI="$GNUTLS_CLI"
 export GNUTLS_SERV="$GNUTLS_SERV"
 
@@ -125,17 +125,17 @@
     echo
 
     echo '#### compat.sh: legacy (SSLv3)'
-    OPENSSL_CMD="$OPENSSL_LEGACY" sh compat.sh -m 'ssl3'
+    OPENSSL="$OPENSSL_LEGACY" sh compat.sh -m 'ssl3'
     echo
 
     echo '#### compat.sh: legacy (null, DES, RC4)'
-    OPENSSL_CMD="$OPENSSL_LEGACY" \
+    OPENSSL="$OPENSSL_LEGACY" \
     GNUTLS_CLI="$GNUTLS_LEGACY_CLI" GNUTLS_SERV="$GNUTLS_LEGACY_SERV" \
     sh compat.sh -e '^$' -f 'NULL\|DES\|RC4\|ARCFOUR'
     echo
 
     echo '#### compat.sh: next (ARIA, ChaCha)'
-    OPENSSL_CMD="$OPENSSL_NEXT" sh compat.sh -e '^$' -f 'ARIA\|CHACHA'
+    OPENSSL="$OPENSSL_NEXT" sh compat.sh -e '^$' -f 'ARIA\|CHACHA'
     echo
 } | tee compat-test-$TEST_OUTPUT
 echo '^^^^^^^^^^^^^^^^ compat.sh ^^^^^^^^^^^^^^^^'
diff --git a/tests/ssl-opt-in-docker.sh b/tests/ssl-opt-in-docker.sh
index 0b76440..ce900e6 100755
--- a/tests/ssl-opt-in-docker.sh
+++ b/tests/ssl-opt-in-docker.sh
@@ -12,7 +12,7 @@
 #
 # Notes for users
 # ---------------
-# If OPENSSL_CMD, GNUTLS_CLI, or GNUTLS_SERV are specified, the path must
+# If OPENSSL, GNUTLS_CLI, or GNUTLS_SERV are specified, the path must
 # correspond to an executable inside the Docker container. The special
 # values "next" and "legacy" are also allowed as shorthand for the
 # installations inside the container.
@@ -38,9 +38,9 @@
 
 source tests/scripts/docker_env.sh
 
-case "${OPENSSL_CMD:-default}" in
-    "legacy")  export OPENSSL_CMD="/usr/local/openssl-1.0.1j/bin/openssl";;
-    "next")    export OPENSSL_CMD="/usr/local/openssl-1.1.1a/bin/openssl";;
+case "${OPENSSL:-default}" in
+    "legacy")  export OPENSSL="/usr/local/openssl-1.0.1j/bin/openssl";;
+    "next")    export OPENSSL="/usr/local/openssl-1.1.1a/bin/openssl";;
     *) ;;
 esac
 
@@ -62,6 +62,6 @@
     -e P_PXY \
     -e GNUTLS_CLI \
     -e GNUTLS_SERV \
-    -e OPENSSL_CMD \
+    -e OPENSSL \
     tests/ssl-opt.sh \
     $@
diff --git a/tests/ssl-opt.sh b/tests/ssl-opt.sh
index 9e5dc6c..94c339e 100755
--- a/tests/ssl-opt.sh
+++ b/tests/ssl-opt.sh
@@ -46,11 +46,22 @@
 : ${P_CLI:=../programs/ssl/ssl_client2}
 : ${P_PXY:=../programs/test/udp_proxy}
 : ${P_QUERY:=../programs/test/query_compile_time_config}
-: ${OPENSSL_CMD:=openssl} # OPENSSL would conflict with the build system
+: ${OPENSSL:=openssl}
 : ${GNUTLS_CLI:=gnutls-cli}
 : ${GNUTLS_SERV:=gnutls-serv}
 : ${PERL:=perl}
 
+# The OPENSSL variable used to be OPENSSL_CMD for historical reasons.
+# To help the migration, error out if the old variable is set,
+# but only if it has a different value than the new one.
+if [ "${OPENSSL_CMD+set}" = set ]; then
+    # the variable is set, we can now check its value
+    if [ "$OPENSSL_CMD" != "$OPENSSL" ]; then
+        echo "Please use OPENSSL instead of OPENSSL_CMD." >&2
+        exit 125
+    fi
+fi
+
 guess_config_name() {
     if git diff --quiet ../include/mbedtls/config.h 2>/dev/null; then
         echo "default"
@@ -62,8 +73,8 @@
 : ${MBEDTLS_TEST_CONFIGURATION:="$(guess_config_name)"}
 : ${MBEDTLS_TEST_PLATFORM:="$(uname -s | tr -c \\n0-9A-Za-z _)-$(uname -m | tr -c \\n0-9A-Za-z _)"}
 
-O_SRV="$OPENSSL_CMD s_server -www -cert data_files/server5.crt -key data_files/server5.key"
-O_CLI="echo 'GET / HTTP/1.0' | $OPENSSL_CMD s_client"
+O_SRV="$OPENSSL s_server -www -cert data_files/server5.crt -key data_files/server5.key"
+O_CLI="echo 'GET / HTTP/1.0' | $OPENSSL s_client"
 G_SRV="$GNUTLS_SERV --x509certfile data_files/server5.crt --x509keyfile data_files/server5.key"
 G_CLI="echo 'GET / HTTP/1.0' | $GNUTLS_CLI --x509cafile data_files/test-ca_cat12.crt"
 TCP_CLIENT="$PERL scripts/tcp_client.pl"
@@ -404,7 +415,7 @@
 # skip next test if OpenSSL doesn't support FALLBACK_SCSV
 requires_openssl_with_fallback_scsv() {
     if [ -z "${OPENSSL_HAS_FBSCSV:-}" ]; then
-        if $OPENSSL_CMD s_client -help 2>&1 | grep fallback_scsv >/dev/null
+        if $OPENSSL s_client -help 2>&1 | grep fallback_scsv >/dev/null
         then
             OPENSSL_HAS_FBSCSV="YES"
         else
@@ -1443,8 +1454,8 @@
         exit 1
     fi
 fi
-if which $OPENSSL_CMD >/dev/null 2>&1; then :; else
-    echo "Command '$OPENSSL_CMD' not found"
+if which $OPENSSL >/dev/null 2>&1; then :; else
+    echo "Command '$OPENSSL' not found"
     exit 1
 fi
 
@@ -1499,7 +1510,7 @@
 # OpenSSL 1.1.1f from Ubuntu 20.04. The syntax was only introduced in
 # OpenSSL 1.1.0 (21e0c1d23afff48601eb93135defddae51f7e2e3) and I can't find
 # a way to discover it from -help, so check the openssl version.
-case $($OPENSSL_CMD version) in
+case $($OPENSSL version) in
     "OpenSSL 0"*|"OpenSSL 1.0"*) :;;
     *)
         O_CLI="$O_CLI -cipher ALL@SECLEVEL=0"