diff --git a/src/sd.rs b/src/sd.rs
index fb4a30997..d61456e1e 100755
--- a/src/sd.rs
+++ b/src/sd.rs
@@ -294,9 +294,9 @@ impl<'d> SdCardDriver<SdMmcHostDriver<'d>> {
             pwr_ctrl_handle: core::ptr::null_mut() as _,
         };
 
-        let mut card: sdmmc_card_t = Default::default();
+        let mut card: alloc::boxed::Box<sdmmc_card_t> = Default::default();
 
-        esp!(unsafe { sdmmc_card_init(&configuration, &mut card) })?;
+        esp!(unsafe { sdmmc_card_init(&configuration, &mut *card) })?;
 
         Ok(Self { _host: host, card })
     }