diff --git a/croaring/Cargo.toml b/croaring/Cargo.toml
index 2eacddc..e4c10e7 100644
--- a/croaring/Cargo.toml
+++ b/croaring/Cargo.toml
@@ -25,7 +25,7 @@ roaring = "0.10"
 criterion = { version = "0.5", features = ["html_reports"] }
 
 [dependencies]
-ffi = { package = "croaring-sys", path = "../croaring-sys", version = "~4.1.1" }
+ffi = { package = "croaring-sys", path = "../croaring-sys", version = "~4.1.2" }
 
 [[bench]]
 name = "benches"
diff --git a/croaring/src/bitmap/mod.rs b/croaring/src/bitmap/mod.rs
index 417c04a..b38fc98 100644
--- a/croaring/src/bitmap/mod.rs
+++ b/croaring/src/bitmap/mod.rs
@@ -67,7 +67,7 @@ use core::marker::PhantomData;
 // &BitmapView and &Bitmap
 #[repr(transparent)]
 pub struct Bitmap {
-    bitmap: ffi::roaring_bitmap_t,
+    pub(crate) bitmap: ffi::roaring_bitmap_t,
 }
 
 unsafe impl Sync for Bitmap {}
diff --git a/croaring/src/bitmap64/ops.rs b/croaring/src/bitmap64/ops.rs
index dc60609..4a22403 100644
--- a/croaring/src/bitmap64/ops.rs
+++ b/croaring/src/bitmap64/ops.rs
@@ -1,4 +1,4 @@
-use crate::Bitmap64;
+use crate::{Bitmap, Bitmap64};
 use core::fmt;
 use core::ops::{BitAnd, BitAndAssign, BitOr, BitOrAssign, BitXor, BitXorAssign, Sub, SubAssign};
 use ffi::roaring64_bitmap_copy;
@@ -45,6 +45,12 @@ impl From<&'_ [u64]> for Bitmap64 {
     }
 }
 
+impl From<Bitmap> for Bitmap64 {
+    fn from(mut value: Bitmap) -> Self {
+        unsafe { Self::take_heap(ffi::roaring64_bitmap_move_from_roaring32(&mut value.bitmap)) }
+    }
+}
+
 impl<const N: usize> From<[u64; N]> for Bitmap64 {
     #[inline]
     #[doc(alias = "roaring64_bitmap_of_ptr")]