diff --git a/changelog/2653.fixed.md b/changelog/2653.fixed.md
new file mode 100644
index 0000000000..fb2885671d
--- /dev/null
+++ b/changelog/2653.fixed.md
@@ -0,0 +1 @@
+Fixed `nix::sys::ptrace::syscall_info`, which was not setting the `data` argument properly, causing garbage values to be returned.
diff --git a/src/sys/ptrace/linux.rs b/src/sys/ptrace/linux.rs
index 8c1a46ba8d..d067ef5789 100644
--- a/src/sys/ptrace/linux.rs
+++ b/src/sys/ptrace/linux.rs
@@ -504,7 +504,7 @@ fn ptrace_get_data<T>(request: Request, pid: Pid) -> Result<T> {
         libc::ptrace(
             request as RequestType,
             libc::pid_t::from(pid),
-            ptr::null_mut::<T>(),
+            std::mem::size_of::<T>(),
             data.as_mut_ptr(),
         )
     };