diff --git a/.github/workflows/build.yml b/.github/workflows/build.yml
index 5898be5f..d7505c48 100644
--- a/.github/workflows/build.yml
+++ b/.github/workflows/build.yml
@@ -18,6 +18,8 @@ jobs:
       matrix:
         os: [ubuntu-latest, windows-latest, macos-latest]
         python-version: ["3.9", "3.13"]
+        java-version: ["8", "21"]
+
 
     steps:
     - uses: actions/checkout@v2
@@ -28,7 +30,7 @@ jobs:
 
     - uses: actions/setup-java@v3
       with:
-        java-version: '8'
+        java-version: ${{matrix.java-version}}
         distribution: 'zulu'
 
     - name: Install PyImageJ
@@ -52,7 +54,7 @@ jobs:
           python -m pip install ruff
           ruff check
           ruff format --check
-        
+
       - name: Validate pyproject.toml
         run: |
           python -m pip install validate-pyproject[all]
diff --git a/conftest.py b/conftest.py
index 45b9ddd7..5538a7ef 100644
--- a/conftest.py
+++ b/conftest.py
@@ -1,8 +1,9 @@
 import argparse
-
+import subprocess
 import pytest
 
 import imagej
+from scyjava import config
 
 
 def pytest_addoption(parser):
@@ -39,12 +40,16 @@ def ij(request):
     Create an ImageJ instance to be used by the whole testing environment
     :param request: Pytest variable passed in to fixtures
     """
+    # get test configuration
     ij_dir = request.config.getoption("--ij")
     legacy = request.config.getoption("--legacy")
     headless = request.config.getoption("--headless")
-
+    # add the nashorn (JavaScript) endpoint if needed,
+    # nashorn was bundled with the JDK from Java 8 to 14
+    if capture_java_version() > 14:
+        config.endpoints.append("org.openjdk.nashorn:nashorn-core")
     imagej.when_imagej_starts(lambda ij: setattr(ij, "_testing", True))
-
+    # initialize the ImageJ gateway
     mode = "headless" if headless else "interactive"
     ij = imagej.init(ij_dir, mode=mode, add_legacy=legacy)
 
@@ -53,6 +58,33 @@ def ij(request):
     ij.dispose()
 
 
+def capture_java_version() -> int:
+    """Capture the installed Java version.
+
+    This function captures the JDK version installed in the current
+    venv without starting the JVM by parsing the Java "-version"
+    output string.
+
+    :return: The major Java version (8, 11, 21 etc...).
+    """
+    try:
+        # capture the Java version string
+        java_ver_str = subprocess.run(
+            ["java", "-version"], capture_output=True, text=True
+        )
+        # extract the Java version from the string
+        java_ver = java_ver_str.stderr.split("\n")[0].split(" ")[2]
+        java_ver = java_ver.strip('"').split(".")
+        major_ver_arr = [int(java_ver[i]) for i in range(2)]
+        # find major Java version
+        if major_ver_arr[0] == 1:
+            return major_ver_arr[1]  # Java 8-10
+        else:
+            return major_ver_arr[0]  # Java 11+
+    except FileNotFoundError:
+        raise RuntimeError("No Java installation found.")
+
+
 def str2bool(v):
     """
     Convert string inputs into bool
diff --git a/dev-environment.yml b/dev-environment.yml
index dabc7567..0e46c865 100644
--- a/dev-environment.yml
+++ b/dev-environment.yml
@@ -24,7 +24,7 @@ dependencies:
   # Project dependencies
   - imglyb >= 2.1.0
   - jgo >= 1.0.3
-  - jpype1 >= 1.3.0
+  - jpype1 >= 1.4.0
   - labeling >= 0.1.14
   - numpy
   - openjdk=11
diff --git a/environment.yml b/environment.yml
index 4fb58f06..edb0b91b 100644
--- a/environment.yml
+++ b/environment.yml
@@ -24,7 +24,7 @@ dependencies:
   # Project dependencies
   - imglyb >= 2.1.0
   - jgo >= 1.0.3
-  - jpype1 >= 1.3.0
+  - jpype1 >= 1.4.0
   - labeling >= 0.1.14
   - numpy
   - openjdk=11
diff --git a/pyproject.toml b/pyproject.toml
index e396b995..c6ea72b0 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -37,7 +37,7 @@ requires-python = ">=3.9"
 dependencies = [
     "imglyb >= 2.1.0",
     "jgo >= 1.0.3",
-    "jpype1 >= 1.3.0",
+    "jpype1 >= 1.4.0",
     "labeling >= 0.1.14",
     "numpy",
     "scyjava >= 1.8.0",