diff --git a/pom.xml b/pom.xml
index 8ed7db1da49..53f493b5c29 100644
--- a/pom.xml
+++ b/pom.xml
@@ -594,11 +594,36 @@ Brotli, Zstandard and ar, cpio, jar, tar, zip, dump, 7z, arj.
           <plugin>
             <groupId>org.apache.maven.plugins</groupId>
             <artifactId>maven-surefire-plugin</artifactId>
-            <configuration>
-              <argLine>
-                ${argLine} --add-opens java.base/java.io=ALL-UNNAMED
-              </argLine>
-            </configuration>
+            <!-- we need jdk > 16 to pass on LegacyContstructorsTest so
+                 we need \-\-add-opens generally. However, we want to test
+                 that unpack200 works with jdk > 16 without \-\-add-opens-->
+            <executions>
+              <execution>
+                <id>default-test</id>
+                <configuration>
+                  <argLine>
+                    ${argLine} --add-opens java.base/java.io=ALL-UNNAMED
+                  </argLine>
+                  <excludes>
+                    <exclude>**/harmony/unpack200/**</exclude>
+                    <!-- Needs low memory: -Xmx80m -->
+                    <exclude>**/SevenZReadSubStreamsInfoTest.java</exclude>
+                  </excludes>
+                </configuration>
+              </execution>
+              <execution>
+                <id>pack200-tests</id>
+                <goals>
+                  <goal>test</goal>
+                </goals>
+                <configuration>
+                  <argLine>${argLine}</argLine>
+                  <includes>
+                    <include>**/harmony/unpack200/**</include>
+                  </includes>
+                </configuration>
+              </execution>
+            </executions>
           </plugin>
         </plugins>
       </build>
diff --git a/src/main/java/org/apache/commons/compress/harmony/unpack200/Archive.java b/src/main/java/org/apache/commons/compress/harmony/unpack200/Archive.java
index 024a9bfc8ea..4ebc30fde1d 100644
--- a/src/main/java/org/apache/commons/compress/harmony/unpack200/Archive.java
+++ b/src/main/java/org/apache/commons/compress/harmony/unpack200/Archive.java
@@ -81,7 +81,8 @@ public Archive(final InputStream inputStream, final JarOutputStream outputStream
         this.inputStream = Pack200UnpackerAdapter.newBoundedInputStream(inputStream);
         this.outputStream = outputStream;
         if (inputStream instanceof FileInputStream) {
-            inputPath = Paths.get(Pack200UnpackerAdapter.readPathString((FileInputStream) inputStream));
+            final String pathString = Pack200UnpackerAdapter.readPathString((FileInputStream) inputStream);
+            inputPath = pathString != null ? Paths.get(pathString) : null;
         } else {
             inputPath = null;
         }
diff --git a/src/main/java/org/apache/commons/compress/harmony/unpack200/Pack200UnpackerAdapter.java b/src/main/java/org/apache/commons/compress/harmony/unpack200/Pack200UnpackerAdapter.java
index cbde81642b4..87ca69df29f 100644
--- a/src/main/java/org/apache/commons/compress/harmony/unpack200/Pack200UnpackerAdapter.java
+++ b/src/main/java/org/apache/commons/compress/harmony/unpack200/Pack200UnpackerAdapter.java
@@ -59,8 +59,26 @@ static BoundedInputStream newBoundedInputStream(final File file) throws IOExcept
         return newBoundedInputStream(file.toPath());
     }
 
+    @SuppressWarnings("resource") // Caller closes.
     private static BoundedInputStream newBoundedInputStream(final FileInputStream fileInputStream) throws IOException {
-        return newBoundedInputStream(readPathString(fileInputStream));
+        final String pathString = readPathString(fileInputStream);
+        if (pathString != null) {
+            return newBoundedInputStream(pathString);
+        }
+        // Reflection failed (e.g., Java 17+ strong encapsulation), fall back to channel size.
+        try {
+            final long size = fileInputStream.getChannel().size();
+            // @formatter:off
+            return BoundedInputStream.builder()
+                    .setInputStream(new BufferedInputStream(fileInputStream))
+                    .setMaxCount(size)
+                    .setPropagateClose(false)
+                    .get();
+            // @formatter:on
+        } catch (final IOException e) {
+            // No limit
+            return BoundedInputStream.builder().setInputStream(new BufferedInputStream(fileInputStream)).get();
+        }
     }
 
     @SuppressWarnings("resource") // Caller closes.
@@ -74,7 +92,10 @@ static BoundedInputStream newBoundedInputStream(final InputStream inputStream) t
             return newBoundedInputStream(BoundedInputStream.builder().setInputStream(inputStream).get());
         }
         if (inputStream instanceof FilterInputStream) {
-            return newBoundedInputStream(unwrap((FilterInputStream) inputStream));
+            final InputStream unwrapped = unwrap((FilterInputStream) inputStream);
+            if (unwrapped != null) {
+                return newBoundedInputStream(unwrapped);
+            }
         }
         if (inputStream instanceof FileInputStream) {
             return newBoundedInputStream((FileInputStream) inputStream);
@@ -140,6 +161,13 @@ private static <T> T readField(final Object object, final String fieldName) {
             return (T) FieldUtils.readField(object, fieldName, true);
         } catch (final IllegalAccessException e) {
             return null;
+        } catch (final RuntimeException e) {
+            // InaccessibleObjectException (Java 9+) extends RuntimeException, not IllegalAccessException.
+            // Thrown when Java 17+ strong encapsulation blocks setAccessible on JDK internal fields.
+            if ("java.lang.reflect.InaccessibleObjectException".equals(e.getClass().getName())) {
+                return null;
+            }
+            throw e;
         }
     }