# Deallocation of nonallocated memory Detects attempts to free nonallocated memory. ## Overview Use this check to detect when you call `free` on memory that you don’t allocate using `malloc`. Attempting to deallocate nonallocated memory can result in a crash. Available in Xcode 7 and later. ### Deallocation of a stack variable in C In the following example, the `value` variable allocates on the stack, and deallocates when the function exits, so calling `free` on it is incorrect: ```occ int value = 42; free(&value); // Error: free called on stack allocated variable ``` #### Solution Don’t call the `free` function on variables that you allocate on the stack. --- Copyright © 2026 Apple Inc. All rights reserved. | [Terms of Use](https://www.apple.com/legal/internet-services/terms/site.html) | [Privacy Policy](https://www.apple.com/privacy/privacy-policy)