diff --git a/tests/scripts/all.sh b/tests/scripts/all.sh
index ee0df0c..6b33960 100755
--- a/tests/scripts/all.sh
+++ b/tests/scripts/all.sh
@@ -32,6 +32,7 @@
 
 MEMORY=0
 FORCE=0
+RELEASE=0
 
 # Default commands, can be overriden by the environment
 : ${OPENSSL:="openssl"}
@@ -48,6 +49,8 @@
     printf "  -h|--help\t\tPrint this help.\n"
     printf "  -m|--memory\t\tAdditional optional memory tests.\n"
     printf "  -f|--force\t\tForce the tests to overwrite any modified files.\n"
+    printf "  -s|--seed\t\tInteger seed value to use for this test run.\n"
+    printf "  -r|--release-test\t\tRun this script in release mode. This fixes the seed value to 1.\n"
     printf "     --out-of-source-dir=<path>\t\tDirectory used for CMake out-of-source build tests."
     printf "     --openssl=<OpenSSL_path>\t\tPath to OpenSSL executable to use for most tests.\n"
     printf "     --openssl-legacy=<OpenSSL_path>\t\tPath to OpenSSL executable to use for legacy tests e.g. SSLv3.\n"
@@ -106,6 +109,13 @@
         --force|-f)
             FORCE=1
             ;;
+        --seed|-s)
+            shift
+            SEED="$1"
+            ;;
+        --release-test|-r)
+            RELEASE=1
+            ;;
         --out-of-source-dir)
             shift
             OUT_OF_SOURCE_DIR="$1"
@@ -171,9 +181,15 @@
     fi
 fi
 
+if [ $RELEASE -eq 1 ]; then
+    # Fix the seed value to 1 to ensure that the tests are deterministic.
+    SEED=1
+fi
+
 msg "info: $0 configuration"
 echo "MEMORY: $MEMORY"
 echo "FORCE: $FORCE"
+echo "SEED: ${SEED-"UNSET"}"
 echo "OPENSSL: $OPENSSL"
 echo "OPENSSL_LEGACY: $OPENSSL_LEGACY"
 echo "GNUTLS_CLI: $GNUTLS_CLI"
@@ -187,6 +203,9 @@
 export GNUTLS_CLI="$GNUTLS_CLI"
 export GNUTLS_SERV="$GNUTLS_SERV"
 
+# Avoid passing --seed flag in every call to ssl-opt.sh
+[ ! -z ${SEED+set} ] && export SEED
+
 # Make sure the tools we need are available.
 check_tools "$OPENSSL" "$OPENSSL_LEGACY" "$GNUTLS_CLI" "$GNUTLS_SERV" \
     "$GNUTLS_LEGACY_CLI" "$GNUTLS_LEGACY_SERV" "doxygen" "dot" \
diff --git a/tests/ssl-opt.sh b/tests/ssl-opt.sh
index d9c45cd..429d9cd 100755
--- a/tests/ssl-opt.sh
+++ b/tests/ssl-opt.sh
@@ -58,6 +58,7 @@
     printf "  -n|--number\tExecute only numbered test (comma-separated, e.g. '245,256')\n"
     printf "  -s|--show-numbers\tShow test numbers in front of test names\n"
     printf "  -p|--preserve-logs\tPreserve logs of successful tests as well\n"
+    printf "     --seed\tInteger seed value to use for this test run\n"
 }
 
 get_options() {
@@ -81,6 +82,9 @@
             -p|--preserve-logs)
                 PRESERVE_LOGS=1
                 ;;
+            --seed)
+                shift; SEED="$1"
+                ;;
             -h|--help)
                 print_usage
                 exit 0
@@ -595,7 +599,7 @@
 # +SRV_PORT will be replaced by either $SRV_PORT or $PXY_PORT later
 P_SRV="$P_SRV server_addr=127.0.0.1 server_port=$SRV_PORT"
 P_CLI="$P_CLI server_addr=127.0.0.1 server_port=+SRV_PORT"
-P_PXY="$P_PXY server_addr=127.0.0.1 server_port=$SRV_PORT listen_addr=127.0.0.1 listen_port=$PXY_PORT"
+P_PXY="$P_PXY server_addr=127.0.0.1 server_port=$SRV_PORT listen_addr=127.0.0.1 listen_port=$PXY_PORT ${SEED:+"seed=$SEED"}"
 O_SRV="$O_SRV -accept $SRV_PORT -dhparam data_files/dhparams.pem"
 O_CLI="$O_CLI -connect localhost:+SRV_PORT"
 G_SRV="$G_SRV -p $SRV_PORT"