diff --git a/tests/tpem_encoder b/tests/tpem_encoder
index 2dbba70a..bc8fb519 100755
--- a/tests/tpem_encoder
+++ b/tests/tpem_encoder
@@ -15,7 +15,8 @@ make-pkey-pem() {
     URI=$1
     OUT=$2
 
-    TMP_FILE=$(mktemp -p "${TMPPDIR}" -t pem-encoder-XXXXXX.cnf)
+    RANDOM_HEX=$(od -A n -N 15 -t x1 /dev/random)
+    TMP_FILE="${TMPPDIR}/pem-encoder-${RANDOM_HEX}.cnf"
     cat > "${TMP_FILE}" << EOF
 asn1=SEQUENCE:pk11-uri
 [pk11-uri]
@@ -32,7 +33,9 @@ sign-verify() {
     PRIV_KEY=$1
     PUB_KEY=$2
     FILE=$3
-    TMP_FILE=$(mktemp -p "${TMPPDIR}" -t sign-verify-pem-encoder-XXXXXX.bin)
+
+    RANDOM_HEX=$(od -A n -N 15 -t x1 /dev/random)
+    TMP_FILE="${TMPPDIR}/sign-verify-pem-encoder-${RANDOM_HEX}.bin"
 
     $CHECKER openssl pkeyutl -sign -rawin -digest sha256 \
             -inkey "${PRIV_KEY}" \
@@ -54,7 +57,7 @@ make-pkey-pem "${PRIURI}" "${TMPPDIR}/priuri-pkey.pem"
 sign-verify "${TMPPDIR}/priuri-pkey.pem" "${PUBURI}" "${TMPPDIR}/64krandom.bin"
 
 RANDOM_HEX=$(od -A n -N 15 -t x1 /dev/random)
-export LABEL_SUFFIX_URI=${RANDOM_HEX// /%}
+export LABEL_SUFFIX_URI=${RANDOM_HEX// /}
 
 export ALGORITHM=rsa
 export ALGORITHM_OPT=rsa_keygen_bits:2048