diff --git a/pdf/src/build.rs b/pdf/src/build.rs
index b85d4cc..addae67 100644
--- a/pdf/src/build.rs
+++ b/pdf/src/build.rs
@@ -157,8 +157,8 @@ pub struct PdfBuilder<SC, OC, L> {
 }
 impl<SC, OC, L> PdfBuilder<SC, OC, L>
 where
-    SC: Cache<Result<AnySync, Arc<PdfError>>>,
-    OC: Cache<Result<Arc<[u8]>, Arc<PdfError>>>,
+    SC: Cache<Result<AnySync, Arc<PdfError>>> + Default,
+    OC: Cache<Result<Arc<[u8]>, Arc<PdfError>>> + Default,
     L: Log,
 {
     pub fn new(fileoptions: FileOptions<'_, SC, OC, L>) -> Self {
diff --git a/pdf/src/content.rs b/pdf/src/content.rs
index ec733b2..0e1a335 100644
--- a/pdf/src/content.rs
+++ b/pdf/src/content.rs
@@ -515,7 +515,7 @@ impl Object for Content {
     }
 }
 
-#[derive(Debug, DataSize, DeepClone)]
+#[derive(Debug, DataSize, DeepClone, Clone)]
 pub struct FormXObject {
     pub stream: Stream<FormDict>,
 }
@@ -539,6 +539,13 @@ impl Object for FormXObject {
         })
     }
 }
+impl ObjectWrite for FormXObject {
+    fn to_primitive(&self, update: &mut impl Updater) -> Result<Primitive> {
+        let mut stream = self.stream.to_pdf_stream(update)?;
+        stream.info.insert("Subtype", Name::from("Form"));
+        Ok(stream.into())
+    }
+}
 
 #[allow(clippy::float_cmp)]  // TODO
 pub fn serialize_ops(mut ops: &[Op]) -> Result<Vec<u8>> {
diff --git a/pdf/src/object/mod.rs b/pdf/src/object/mod.rs
index cc3e022..87d8a70 100644
--- a/pdf/src/object/mod.rs
+++ b/pdf/src/object/mod.rs
@@ -247,6 +247,11 @@ impl<T> From<RcRef<T>> for Primitive {
         Primitive::Reference(value.inner)
     }
 }
+impl<T> From<RcRef<T>> for Ref<T> {
+    fn from(value: RcRef<T>) -> Self {
+        value.get_ref()
+    }
+}
 
 impl<T> RcRef<T> {
     pub fn new(inner: PlainRef, data: Shared<T>) -> RcRef<T> {
@@ -387,6 +392,11 @@ impl<T> From<Shared<T>> for MaybeRef<T> {
         MaybeRef::Direct(r)
     }
 }
+impl<T> From<T> for MaybeRef<T> {
+    fn from(t: T) -> MaybeRef<T> {
+        MaybeRef::Direct(t.into())
+    }
+}
 impl<T> From<MaybeRef<T>> for Shared<T> {
     fn from(r: MaybeRef<T>) -> Shared<T> {
         match r {