diff --git a/tests/compat.sh b/tests/compat.sh
index 53db751..78a6892 100755
--- a/tests/compat.sh
+++ b/tests/compat.sh
@@ -112,12 +112,12 @@
 print_usage() {
     echo "Usage: $0"
     printf "  -h|--help\tPrint this help.\n"
-    printf "  -f|--filter\tOnly matching ciphersuites are tested (Default: '$FILTER')\n"
-    printf "  -e|--exclude\tMatching ciphersuites are excluded (Default: '$EXCLUDE')\n"
-    printf "  -m|--modes\tWhich modes to perform (Default: '$MODES')\n"
-    printf "  -t|--types\tWhich key exchange type to perform (Default: '$TYPES')\n"
-    printf "  -V|--verify\tWhich verification modes to perform (Default: '$VERIFIES')\n"
-    printf "  -p|--peers\tWhich peers to use (Default: '$PEERS')\n"
+    printf "  -f|--filter\tOnly matching ciphersuites are tested (Default: '%s')\n" "$FILTER"
+    printf "  -e|--exclude\tMatching ciphersuites are excluded (Default: '%s')\n" "$EXCLUDE"
+    printf "  -m|--modes\tWhich modes to perform (Default: '%s')\n" "$MODES"
+    printf "  -t|--types\tWhich key exchange type to perform (Default: '%s')\n" "$TYPES"
+    printf "  -V|--verify\tWhich verification modes to perform (Default: '%s')\n" "$VERIFIES"
+    printf "  -p|--peers\tWhich peers to use (Default: '%s')\n" "$PEERS"
     printf "            \tAlso available: GnuTLS (needs v3.2.15 or higher)\n"
     printf "  -M|--memcheck\tCheck memory leaks and errors.\n"
     printf "  -v|--verbose\tSet verbose output.\n"
@@ -1010,7 +1010,7 @@
     VERIF=$(echo $VERIFY | tr '[:upper:]' '[:lower:]')
     TITLE="`echo $1 | head -c1`->`echo $SERVER_NAME | head -c1`"
     TITLE="$TITLE $MODE,$VERIF $2"
-    printf "$TITLE "
+    printf "%s " "$TITLE"
     LEN=$(( 72 - `echo "$TITLE" | wc -c` ))
     for i in `seq 1 $LEN`; do printf '.'; done; printf ' '
 
diff --git a/tests/scripts/check-names.sh b/tests/scripts/check-names.sh
index bce3fca..e8f843b 100755
--- a/tests/scripts/check-names.sh
+++ b/tests/scripts/check-names.sh
@@ -92,7 +92,7 @@
 diff macros identifiers | sed -n -e 's/< //p' > actual-macros
 
 for THING in actual-macros enum-consts; do
-    printf "Names of $THING: "
+    printf 'Names of %s: ' "$THING"
     test -r $THING
     BAD=$( grep -v '^MBEDTLS_[0-9A-Z_]*[0-9A-Z]$\|^YOTTA_[0-9A-Z_]*[0-9A-Z]$' $THING || true )
     if [ "x$BAD" = "x" ]; then
@@ -105,7 +105,7 @@
 done
 
 for THING in identifiers; do
-    printf "Names of $THING: "
+    printf 'Names of %s: ' "$THING"
     test -r $THING
     BAD=$( grep -v '^mbedtls_[0-9a-z_]*[0-9a-z]$' $THING || true )
     if [ "x$BAD" = "x" ]; then
diff --git a/tests/ssl-opt.sh b/tests/ssl-opt.sh
index 7fc0b0f..72d0eb8 100755
--- a/tests/ssl-opt.sh
+++ b/tests/ssl-opt.sh
@@ -254,7 +254,7 @@
     fi
 
     LINE="$LINE$1"
-    printf "$LINE "
+    printf "%s " "$LINE"
     LEN=$(( 72 - `echo "$LINE" | wc -c` ))
     for i in `seq 1 $LEN`; do printf '.'; done
     printf ' '
@@ -518,12 +518,12 @@
         fi
 
         check_osrv_dtls
-        printf "# $NAME\n$SRV_CMD\n" > $SRV_OUT
+        printf '# %s\n%s\n' "$NAME" "$SRV_CMD" > $SRV_OUT
         provide_input | $SRV_CMD >> $SRV_OUT 2>&1 &
         SRV_PID=$!
         wait_server_start "$SRV_PORT" "$SRV_PID"
 
-        printf "# $NAME\n$CLI_CMD\n" > $CLI_OUT
+        printf '# %s\n%s\n' "$NAME" "$CLI_CMD" > $CLI_OUT
         eval "$CLI_CMD" >> $CLI_OUT 2>&1 &
         wait_client_done
 
@@ -1699,14 +1699,14 @@
 MAX_CONTENT_LEN_CONFIG=$( ../scripts/config.pl get MBEDTLS_SSL_MAX_CONTENT_LEN)
 
 if [ -n "$MAX_CONTENT_LEN_CONFIG" ] && [ "$MAX_CONTENT_LEN_CONFIG" -ne "$MAX_CONTENT_LEN_EXPECT" ]; then
-    printf "The ${CONFIG_H} file contains a value for the configuration of\n"
-    printf "MBEDTLS_SSL_MAX_CONTENT_LEN that is different from the script’s\n"
-    printf "test value of ${MAX_CONTENT_LEN_EXPECT}. \n"
-    printf "\n"
-    printf "The tests assume this value and if it changes, the tests in this\n"
-    printf "script should also be adjusted.\n"
-    printf "\n"
+  cat <<EOF
+The ${CONFIG_H} file contains a value for the configuration of
+MBEDTLS_SSL_MAX_CONTENT_LEN that is different from the script’s
+test value of ${MAX_CONTENT_LEN_EXPECT}.
 
+The tests assume this value and if it changes, the tests in this
+script should also be adjusted.
+EOF
     exit 1
 fi
 
@@ -2644,14 +2644,14 @@
 MAX_IM_CA_CONFIG=$( ../scripts/config.pl get MBEDTLS_X509_MAX_INTERMEDIATE_CA)
 
 if [ -n "$MAX_IM_CA_CONFIG" ] && [ "$MAX_IM_CA_CONFIG" -ne "$MAX_IM_CA" ]; then
-    printf "The ${CONFIG_H} file contains a value for the configuration of\n"
-    printf "MBEDTLS_X509_MAX_INTERMEDIATE_CA that is different from the script’s\n"
-    printf "test value of ${MAX_IM_CA}. \n"
-    printf "\n"
-    printf "The tests assume this value and if it changes, the tests in this\n"
-    printf "script should also be adjusted.\n"
-    printf "\n"
+    cat <<EOF
+${CONFIG_H} contains a value for the configuration of
+MBEDTLS_X509_MAX_INTERMEDIATE_CA that is different from the script's
+test value of ${MAX_IM_CA}.
 
+The tests assume this value and if it changes, the tests in this
+script should also be adjusted.
+EOF
     exit 1
 fi