diff --git a/glib/src/variant_iter.rs b/glib/src/variant_iter.rs
index b4061728a441..e0997f651b10 100644
--- a/glib/src/variant_iter.rs
+++ b/glib/src/variant_iter.rs
@@ -117,13 +117,13 @@ impl<'a> VariantStrIter<'a> {
 
     fn impl_get(&self, i: usize) -> &'a str {
         unsafe {
-            let p: *mut libc::c_char = std::ptr::null_mut();
+            let mut p: *mut libc::c_char = std::ptr::null_mut();
             let s = b"&s\0";
             ffi::g_variant_get_child(
                 self.variant.to_glib_none().0,
                 i,
                 s as *const u8 as *const _,
-                &p,
+                &mut p,
                 std::ptr::null::<i8>(),
             );
             let p = std::ffi::CStr::from_ptr(p);