diff --git a/src/alloc/allocext/linux.rs b/src/alloc/allocext/linux.rs
index bcc5512..9ff23d3 100644
--- a/src/alloc/allocext/linux.rs
+++ b/src/alloc/allocext/linux.rs
@@ -15,12 +15,12 @@ mod memfd_secret_alloc {
     use super::*;
     use core::convert::TryInto;
 
-    /// Allocate memfd_secret with given size and optionally at given address ptr
+    /// Allocate memfd_secret with given size at given address ptr
     /// Returns tuple of ptr to memory and file descriptor of memfd_secret
     #[inline]
     pub unsafe fn alloc_memfd_secret_at_ptr(
         size: usize,
-        ptr: Option<*mut libc::c_void>,
+        ptr: *mut libc::c_void,
     ) -> Option<(NonNull<u8>, libc::c_int)> {
         let fd: Result<libc::c_int, _> = libc::syscall(libc::SYS_memfd_secret, 0).try_into();
 
@@ -29,23 +29,25 @@ mod memfd_secret_alloc {
         // File size is set using ftruncate
         let _ = libc::ftruncate(fd, size as libc::off_t);
 
-        let ptr = libc::mmap(
-            ptr.unwrap_or_else(ptr::null_mut),
+        let ptr_out = libc::mmap(
+            ptr,
             size,
             Prot::ReadWrite,
-            libc::MAP_SHARED
-                | if ptr.is_some() { libc::MAP_FIXED } else { 0 }
-                | MAP_LOCKED
-                | MAP_POPULATE,
+            libc::MAP_SHARED | libc::MAP_FIXED | MAP_LOCKED | MAP_POPULATE,
             fd,
             0,
         );
 
-        if ptr == libc::MAP_FAILED {
+        if ptr_out == libc::MAP_FAILED {
             return None;
         }
 
-        NonNull::new(ptr as *mut u8).map(|ptr| (ptr, fd))
+        if ptr_out != ptr {
+            libc::munmap(ptr_out, size);
+            return None;
+        }
+
+        NonNull::new(ptr_out as *mut u8).map(|ptr| (ptr, fd))
     }
 }
 
@@ -95,7 +97,7 @@ unsafe fn _memfd_secret(size: usize) -> Option<*mut u8> {
 
     let unprotected_ptr = base_ptr.add(front_guard_size);
     let Some((unprotected_ptr_val, fd)) =
-        alloc_memfd_secret_at_ptr(unprotected_size, Some(unprotected_ptr as *mut libc::c_void))
+        alloc_memfd_secret_at_ptr(unprotected_size, unprotected_ptr as *mut libc::c_void)
     else {
         libc::munmap(base_ptr_stored as *mut libc::c_void, PAGE_SIZE);
         libc::munmap(base_ptr as *mut libc::c_void, total_size);