diff --git a/src/header/stdlib/mod.rs b/src/header/stdlib/mod.rs
index 7632f2c237..d9c27f24ef 100644
--- a/src/header/stdlib/mod.rs
+++ b/src/header/stdlib/mod.rs
@@ -1157,10 +1157,10 @@ pub unsafe extern "C" fn qsort_r(
     if let Some(comp) = compar {
         for i in 0..nel {
             for j in (i + 1)..nel {
-                let a = base.cast::<u8>().add(i * width).cast::<c_void>();
-                let b = base.cast::<u8>().add(j * width).cast::<c_void>();
+                let a = unsafe { base.cast::<u8>().add(i * width).cast::<c_void>() };
+                let b = unsafe { base.cast::<u8>().add(j * width).cast::<c_void>() };
                 if comp(a, b, arg) > 0 {
-                    ptr::swap_nonoverlapping(a.cast::<u8>(), b.cast::<u8>(), width);
+                    unsafe { ptr::swap_nonoverlapping(a.cast::<u8>(), b.cast::<u8>(), width) };
                 }
             }
         }