diff --git a/lib/host-permissions.ts b/lib/host-permissions.ts
index 703f7318..6dc2cc78 100644
--- a/lib/host-permissions.ts
+++ b/lib/host-permissions.ts
@@ -15,6 +15,20 @@ type PermissionRule = {
     action: PermissionAction
 }
 
+const findLastMatchingRule = (
+    rules: PermissionRule[],
+    predicate: (rule: PermissionRule) => boolean,
+): PermissionRule | undefined => {
+    for (let index = rules.length - 1; index >= 0; index -= 1) {
+        const rule = rules[index]
+        if (rule && predicate(rule)) {
+            return rule
+        }
+    }
+
+    return undefined
+}
+
 const wildcardMatch = (value: string, pattern: string): boolean => {
     const normalizedValue = value.replaceAll("\\", "/")
     let escaped = pattern
@@ -55,7 +69,7 @@ const getPermissionRules = (permissionConfigs: PermissionConfig[]): PermissionRu
 }
 
 export const compressDisabledByOpencode = (...permissionConfigs: PermissionConfig[]): boolean => {
-    const match = getPermissionRules(permissionConfigs).findLast((rule) =>
+    const match = findLastMatchingRule(getPermissionRules(permissionConfigs), (rule) =>
         wildcardMatch("compress", rule.permission),
     )
 
@@ -83,5 +97,5 @@ export const hasExplicitToolPermission = (
     permissionConfig: PermissionConfig,
     tool: string,
 ): boolean => {
-    return permissionConfig ? Object.hasOwn(permissionConfig, tool) : false
+    return permissionConfig ? Object.prototype.hasOwnProperty.call(permissionConfig, tool) : false
 }
diff --git a/tests/host-permissions.test.ts b/tests/host-permissions.test.ts
index 9e704733..81b84e42 100644
--- a/tests/host-permissions.test.ts
+++ b/tests/host-permissions.test.ts
@@ -67,7 +67,38 @@ test("pattern-specific denies do not disable the whole tool", () => {
     )
 })
 
+test("compress permission resolution works without Array.findLast", () => {
+    const originalFindLast = Array.prototype.findLast
+
+    try {
+        delete (Array.prototype as Array<unknown> & { findLast?: unknown }).findLast
+
+        assert.equal(
+            compressDisabledByOpencode({
+                "*": "deny",
+                compress: "allow",
+            }),
+            false,
+        )
+    } finally {
+        Array.prototype.findLast = originalFindLast
+    }
+})
+
 test("explicit compress permissions are detected", () => {
     assert.equal(hasExplicitToolPermission({ compress: "ask" }, "compress"), true)
     assert.equal(hasExplicitToolPermission({ "*": "deny" }, "compress"), false)
 })
+
+test("explicit permission detection works without Object.hasOwn", () => {
+    const originalHasOwn = Object.hasOwn
+
+    try {
+        delete (Object as typeof Object & { hasOwn?: unknown }).hasOwn
+
+        assert.equal(hasExplicitToolPermission({ compress: "ask" }, "compress"), true)
+        assert.equal(hasExplicitToolPermission({ "*": "deny" }, "compress"), false)
+    } finally {
+        Object.hasOwn = originalHasOwn
+    }
+})