diff --git a/.release-please-manifest.json b/.release-please-manifest.json
index 96f1cd9..9049e2f 100644
--- a/.release-please-manifest.json
+++ b/.release-please-manifest.json
@@ -1,3 +1,3 @@
 {
-  ".": "1.3.0"
+  ".": "1.3.1"
 }
diff --git a/CHANGELOG.md b/CHANGELOG.md
index 4dffe66..bf8c798 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,5 +1,13 @@
 # Changelog
 
+## 1.3.1 (2026-08-20)
+
+Full Changelog: [v1.3.0...v1.3.1](https://github.com/parallel-web/parallel-sdk-typescript/compare/v1.3.0...v1.3.1)
+
+### Chores
+
+* **internal:** allow the mock server port to be set with STAINLESS_MOCK_PORT ([9f170dc](https://github.com/parallel-web/parallel-sdk-typescript/commit/9f170dc1affef292866d85f35a0bba578778967e))
+
 ## 1.3.0 (2026-08-12)
 
 Full Changelog: [v1.2.0...v1.3.0](https://github.com/parallel-web/parallel-sdk-typescript/compare/v1.2.0...v1.3.0)
diff --git a/package.json b/package.json
index d225fe5..bf5d623 100644
--- a/package.json
+++ b/package.json
@@ -1,6 +1,6 @@
 {
   "name": "parallel-web",
-  "version": "1.3.0",
+  "version": "1.3.1",
   "description": "The official TypeScript library for the Parallel API",
   "author": "Parallel <support@parallel.ai>",
   "types": "dist/index.d.ts",
diff --git a/scripts/mock b/scripts/mock
index feebe5e..984e1c0 100755
--- a/scripts/mock
+++ b/scripts/mock
@@ -4,6 +4,11 @@ set -e
 
 cd "$(dirname "$0")/.."
 
+if [ "$1" == "--install" ]; then
+  npm exec --package=@stdy/cli@0.22.1 -- steady --version
+  exit 0
+fi
+
 if [[ -n "$1" && "$1" != '--'* ]]; then
   URL="$1"
   shift
@@ -20,16 +25,18 @@ fi
 echo "==> Starting mock server with URL ${URL}"
 
 # Run steady mock on the given spec
+MOCK_PORT="${STAINLESS_MOCK_PORT:-4010}"
+
 if [ "$1" == "--daemon" ]; then
   # Pre-install the package so the download doesn't eat into the startup timeout
   npm exec --package=@stdy/cli@0.22.1 -- steady --version
 
-  npm exec --package=@stdy/cli@0.22.1 -- steady --host 127.0.0.1 -p 4010 --validator-query-array-format=comma --validator-form-array-format=comma --validator-query-object-format=brackets --validator-form-object-format=brackets "$URL" &> .stdy.log &
+  npm exec --package=@stdy/cli@0.22.1 -- steady --host 127.0.0.1 -p "$MOCK_PORT" --validator-query-array-format=comma --validator-form-array-format=comma --validator-query-object-format=brackets --validator-form-object-format=brackets "$URL" &> .stdy.log &
 
   # Wait for server to come online via health endpoint (max 30s)
   echo -n "Waiting for server"
   attempts=0
-  while ! curl --silent --fail "http://127.0.0.1:4010/_x-steady/health" >/dev/null 2>&1; do
+  while ! curl --silent --fail "http://127.0.0.1:$MOCK_PORT/_x-steady/health" >/dev/null 2>&1; do
     if ! kill -0 $! 2>/dev/null; then
       echo
       cat .stdy.log
@@ -48,5 +55,5 @@ if [ "$1" == "--daemon" ]; then
 
   echo
 else
-  npm exec --package=@stdy/cli@0.22.1 -- steady --host 127.0.0.1 -p 4010 --validator-query-array-format=comma --validator-form-array-format=comma --validator-query-object-format=brackets --validator-form-object-format=brackets "$URL"
+  npm exec --package=@stdy/cli@0.22.1 -- steady --host 127.0.0.1 -p "$MOCK_PORT" --validator-query-array-format=comma --validator-form-array-format=comma --validator-query-object-format=brackets --validator-form-object-format=brackets "$URL"
 fi
diff --git a/scripts/test b/scripts/test
index 19b8d0c..da6c10a 100755
--- a/scripts/test
+++ b/scripts/test
@@ -9,8 +9,10 @@ GREEN='\033[0;32m'
 YELLOW='\033[0;33m'
 NC='\033[0m' # No Color
 
+MOCK_PORT="${STAINLESS_MOCK_PORT:-4010}"
+
 function steady_is_running() {
-  curl --silent "http://127.0.0.1:4010/_x-steady/health" >/dev/null 2>&1
+  curl --silent "http://127.0.0.1:$MOCK_PORT/_x-steady/health" >/dev/null 2>&1
 }
 
 kill_server_on_port() {
@@ -27,7 +29,7 @@ function is_overriding_api_base_url() {
 
 if ! is_overriding_api_base_url && ! steady_is_running ; then
   # When we exit this script, make sure to kill the background mock server process
-  trap 'kill_server_on_port 4010' EXIT
+  trap 'kill_server_on_port "$MOCK_PORT"' EXIT
 
   # Start the dev server
   ./scripts/mock --daemon
@@ -43,7 +45,7 @@ elif ! steady_is_running ; then
   echo -e "To run the server, pass in the path or url of your OpenAPI"
   echo -e "spec to the steady command:"
   echo
-  echo -e "  \$ ${YELLOW}npm exec --package=@stdy/cli@0.22.1 -- steady path/to/your.openapi.yml --host 127.0.0.1 -p 4010 --validator-query-array-format=comma --validator-form-array-format=comma --validator-query-object-format=brackets --validator-form-object-format=brackets${NC}"
+  echo -e "  \$ ${YELLOW}npm exec --package=@stdy/cli@0.22.1 -- steady path/to/your.openapi.yml --host 127.0.0.1 -p $MOCK_PORT --validator-query-array-format=comma --validator-form-array-format=comma --validator-query-object-format=brackets --validator-form-object-format=brackets${NC}"
   echo
 
   exit 1
@@ -52,5 +54,9 @@ else
   echo
 fi
 
+if [ -n "${STAINLESS_MOCK_PORT:-}" ] && ! is_overriding_api_base_url ; then
+  export TEST_API_BASE_URL="http://127.0.0.1:$MOCK_PORT"
+fi
+
 echo "==> Running tests"
 ./node_modules/.bin/jest "$@"
diff --git a/src/version.ts b/src/version.ts
index 39fa5bc..8d95974 100644
--- a/src/version.ts
+++ b/src/version.ts
@@ -1 +1 @@
-export const VERSION = '1.3.0'; // x-release-please-version
+export const VERSION = '1.3.1'; // x-release-please-version