diff --git a/src/main/java/org/apache/commons/jexl3/introspection/JexlSandbox.java b/src/main/java/org/apache/commons/jexl3/introspection/JexlSandbox.java
index 2ce5db986..efb4077cf 100644
--- a/src/main/java/org/apache/commons/jexl3/introspection/JexlSandbox.java
+++ b/src/main/java/org/apache/commons/jexl3/introspection/JexlSandbox.java
@@ -249,6 +249,16 @@ public String execute(final String clazz, final String name) {
         return "".equals(name) && m != null ? clazz : m;
     }
 
+    /**
+     * Gets the set of permissions associated to a class.
+     *
+     * @param clazz the class name
+     * @return the defined permissions or an all-allow permission instance if none were defined
+     */
+    public Permissions get(final String clazz) {
+        return get(forName(clazz));
+    }
+
     /**
      * Gets the permissions associated to a class.
      *
@@ -259,80 +269,55 @@ public String execute(final String clazz, final String name) {
     public Permissions get(final Class<?> clazz) {
         // argument clazz can not be null since permissions would be not null and block:
         // we only store the result for classes we actively seek permissions for.
-        return clazz == null ? BLOCK_ALL : compute(clazz);
+        return compute(clazz, true);
     }
 
-    private static Permissions inheritable(Permissions p) {
+    private static Permissions inheritable(final Permissions p) {
         return p != null && p.isInheritable() ? p : null;
     }
 
-    /**
-     * Find first inherited interface that defines permissions through recursion.
-     * @param clazz the clazz
-     * @return the array of all its interfaces
-     */
-    private Permissions computeInterfaces(final Class<?> clazz) {
-        Permissions permissions = inheritable(sandbox.get(clazz.getName()));
-        if (permissions == null) {
-            final Class<?>[] interfaces = clazz.getInterfaces();
-            for (int i = 0; permissions == null && i < interfaces.length; ++i) {
-                permissions = computeInterfaces(interfaces[i]);
-            }
-        }
-        return permissions;
-    }
-
     /**
      * Computes and optionally stores the permissions associated to a class.
      *
      * @param clazz the class
+     * @param store whether the computed permissions should be stored in the sandbox
      * @return the permissions
      */
-    private Permissions compute(final Class<?> clazz) {
-        Permissions permissions = sandbox.get(clazz.getName());
+    private Permissions compute(final Class<?> clazz, final boolean store) {
+        // belt and suspender; recursion should not lead here
+        if (clazz == null) {
+            return BLOCK_ALL;
+        }
+        final String className = clazz.getName();
+        Permissions permissions = sandbox.get(className);
         if (permissions == null) {
             if (inherit) {
                 // find first inherited interface that defines permissions
                 final Class<?>[] interfaces = clazz.getInterfaces();
                 for (int i = 0; permissions == null && i < interfaces.length; ++i) {
-                    permissions = computeInterfaces(interfaces[i]);
+                    permissions = inheritable(compute(interfaces[i], false));
                 }
                 // nothing defined yet, find first superclass that defines permissions
                 if (permissions == null) {
-                    // let's walk all super classes
-                    for (Class<?> zuper = clazz.getSuperclass();
-                         permissions == null && zuper != null;
-                         zuper = zuper.getSuperclass()) {
-                        permissions = inheritable(sandbox.get(zuper.getName()));
+                    // let's recurse on super classes
+                    Class<?> superClazz = clazz.getSuperclass();
+                    if (Object.class != superClazz) {
+                        permissions = inheritable(compute(superClazz, false));
                     }
                 }
             }
-            // nothing was determined through inheritance
+            // nothing was inheritable
             if (permissions == null) {
                 permissions = allow ? ALLOW_ALL : BLOCK_ALL;
             }
             // store the info to avoid doing this costly look-up
-            sandbox.put(clazz.getName(), permissions);
+            if (store) {
+                sandbox.put(className, permissions);
+            }
         }
         return permissions;
     }
 
-    /**
-     * Gets the set of permissions associated to a class.
-     *
-     * @param clazz the class name
-     * @return the defined permissions or an all-allow permission instance if none were defined
-     */
-    public Permissions get(final String clazz) {
-        if (inherit) {
-            return get(forName(clazz));
-        }
-        final Permissions permissions = sandbox.get(clazz);
-        if (permissions == null) {
-            return allow ? ALLOW_ALL : BLOCK_ALL;
-        }
-        return permissions;
-    }
 
     /**
      * Creates the set of permissions for a given class.
diff --git a/src/test/java/org/apache/commons/jexl3/introspection/SandboxTest.java b/src/test/java/org/apache/commons/jexl3/introspection/SandboxTest.java
index 229d21c5a..aea2cac63 100644
--- a/src/test/java/org/apache/commons/jexl3/introspection/SandboxTest.java
+++ b/src/test/java/org/apache/commons/jexl3/introspection/SandboxTest.java
@@ -604,18 +604,16 @@ static class A implements I{}
     static class B extends A{}
 
     @Test
-    void testPermission0() {
-        JexlSandbox sandbox = new JexlSandbox(false, true);
-        sandbox.permissions(I.class.getName(), true, true, true, false);
-        System.out.println("permission A=" + sandbox.get(A.class.getName()).write());
-        System.out.println("permission B=" + sandbox.get(B.class.getName()).write());
-    }
-    @Test
-    void testPermission1() {
-        JexlSandbox sandbox = new JexlSandbox(false, true);
-        sandbox.permissions(I.class.getName(), true, true, true, false);
-        System.out.println("permission B=" + sandbox.get(B.class.getName()).write());
-        System.out.println("permission A=" + sandbox.get(A.class.getName()).write());
+    void testPermissionOrder() {
+        // permissions should not be dependent on order of evaluation
+        JexlSandbox sandboxAB = new JexlSandbox(false, true);
+        sandboxAB.permissions(I.class.getName(), true, true, true, false);
+        assertEquals("allow{all}", sandboxAB.get(A.class.getName()).write().toString());
+        assertEquals("allow{all}", sandboxAB.get(B.class.getName()).write().toString());
+        JexlSandbox sandboxBA = new JexlSandbox(false, true);
+        sandboxBA.permissions(I.class.getName(), true, true, true, false);
+        assertEquals("allow{all}", sandboxBA.get(B.class.getName()).write().toString());
+        assertEquals("allow{all}", sandboxBA.get(A.class.getName()).write().toString());
     }
 
     @Test