diff --git a/schemars/src/_private.rs b/schemars/src/_private.rs
new file mode 100644
index 0000000..4d1c31f
--- /dev/null
+++ b/schemars/src/_private.rs
@@ -0,0 +1,49 @@
+use crate::flatten::Merge;
+use crate::gen::SchemaGenerator;
+use crate::schema::{Metadata, Schema, SchemaObject};
+use crate::JsonSchema;
+
+// Helper for generating schemas for flattened `Option` fields.
+pub fn json_schema_for_flatten<T: ?Sized + JsonSchema>(gen: &mut SchemaGenerator) -> Schema {
+    let mut schema = T::_schemars_private_non_optional_json_schema(gen);
+    if T::_schemars_private_is_option() {
+        if let Schema::Object(SchemaObject {
+            object: Some(ref mut object_validation),
+            ..
+        }) = schema
+        {
+            object_validation.required.clear();
+        }
+    }
+    schema
+}
+
+// Helper for generating schemas for `Option` fields.
+pub fn add_schema_as_property<T: ?Sized + JsonSchema>(
+    gen: &mut SchemaGenerator,
+    parent: &mut SchemaObject,
+    name: String,
+    metadata: Option<Metadata>,
+    required: bool,
+) {
+    let mut schema = gen.subschema_for::<T>();
+    schema = apply_metadata(schema, metadata);
+
+    let object = parent.object();
+    if required && !T::_schemars_private_is_option() {
+        object.required.insert(name.clone());
+    }
+    object.properties.insert(name, schema);
+}
+
+pub fn apply_metadata(schema: Schema, metadata: Option<Metadata>) -> Schema {
+    match metadata {
+        None => schema,
+        Some(ref metadata) if *metadata == Metadata::default() => schema,
+        Some(metadata) => {
+            let mut schema_obj = schema.into_object();
+            schema_obj.metadata = Some(Box::new(metadata)).merge(schema_obj.metadata);
+            Schema::Object(schema_obj)
+        }
+    }
+}
diff --git a/schemars/src/gen.rs b/schemars/src/gen.rs
index 72c1700..2634e12 100644
--- a/schemars/src/gen.rs
+++ b/schemars/src/gen.rs
@@ -7,7 +7,6 @@ There are two main types in this module:two main types in this module:
 * [`SchemaGenerator`], which manages the generation of a schema document.
 */
 
-use crate::flatten::Merge;
 use crate::schema::*;
 use crate::{visit::*, JsonSchema, Map};
 use dyn_clone::DynClone;
@@ -422,22 +421,6 @@ impl SchemaGenerator {
         }
     }
 
-    /// This function is only public for use by schemars_derive.
-    ///
-    /// It should not be considered part of the public API.
-    #[doc(hidden)]
-    pub fn apply_metadata(&self, schema: Schema, metadata: Option<Metadata>) -> Schema {
-        match metadata {
-            None => schema,
-            Some(ref metadata) if *metadata == Metadata::default() => schema,
-            Some(metadata) => {
-                let mut schema_obj = schema.into_object();
-                schema_obj.metadata = Some(Box::new(metadata)).merge(schema_obj.metadata);
-                Schema::Object(schema_obj)
-            }
-        }
-    }
-
     fn json_schema_internal<T: ?Sized + JsonSchema>(&mut self, name: &str) -> Schema {
         struct PendingSchemaState<'a> {
             gen: &'a mut SchemaGenerator,
diff --git a/schemars/src/json_schema_impls/core.rs b/schemars/src/json_schema_impls/core.rs
index 5cefbdd..10f9f0f 100644
--- a/schemars/src/json_schema_impls/core.rs
+++ b/schemars/src/json_schema_impls/core.rs
@@ -45,30 +45,12 @@ impl<T: JsonSchema> JsonSchema for Option<T> {
         schema
     }
 
-    fn json_schema_for_flatten(gen: &mut SchemaGenerator) -> Schema {
-        let mut schema = T::json_schema_for_flatten(gen);
-        if let Schema::Object(SchemaObject {
-            object: Some(ref mut object_validation),
-            ..
-        }) = schema
-        {
-            object_validation.required.clear();
-        }
-        schema
+    fn _schemars_private_non_optional_json_schema(gen: &mut SchemaGenerator) -> Schema {
+        T::_schemars_private_non_optional_json_schema(gen)
     }
 
-    fn add_schema_as_property(
-        gen: &mut SchemaGenerator,
-        parent: &mut SchemaObject,
-        name: String,
-        metadata: Option<Metadata>,
-        _required: bool,
-    ) {
-        let mut schema = gen.subschema_for::<Self>();
-        schema = gen.apply_metadata(schema, metadata);
-
-        let object = parent.object();
-        object.properties.insert(name, schema);
+    fn _schemars_private_is_option() -> bool {
+        true
     }
 }
 
diff --git a/schemars/src/json_schema_impls/mod.rs b/schemars/src/json_schema_impls/mod.rs
index d114ac4..ff2e1e7 100644
--- a/schemars/src/json_schema_impls/mod.rs
+++ b/schemars/src/json_schema_impls/mod.rs
@@ -21,18 +21,12 @@ macro_rules! forward_impl {
                 <$target>::json_schema(gen)
             }
 
-            fn json_schema_for_flatten(gen: &mut SchemaGenerator) -> Schema {
-                <$target>::json_schema_for_flatten(gen)
+            fn _schemars_private_non_optional_json_schema(gen: &mut SchemaGenerator) -> Schema {
+                <$target>::_schemars_private_non_optional_json_schema(gen)
             }
 
-            fn add_schema_as_property(
-                gen: &mut SchemaGenerator,
-                parent: &mut crate::schema::SchemaObject,
-                name: String,
-                metadata: Option<crate::schema::Metadata>,
-                required: bool,
-            ) {
-                <$target>::add_schema_as_property(gen, parent, name, metadata, required)
+            fn _schemars_private_is_option() -> bool {
+                <$target>::_schemars_private_is_option()
             }
         }
     };
diff --git a/schemars/src/lib.rs b/schemars/src/lib.rs
index 2957fc4..e400ccf 100644
--- a/schemars/src/lib.rs
+++ b/schemars/src/lib.rs
@@ -301,6 +301,10 @@ mod ser;
 #[macro_use]
 mod macros;
 
+/// This module is only public for use by `schemars_derive`. It should not need to be used by code
+/// outside of `schemars`, and should not be considered part of the public API.
+#[doc(hidden)]
+pub mod _private;
 pub mod gen;
 pub mod schema;
 pub mod visit;
@@ -314,7 +318,7 @@ pub use schemars_derive::*;
 #[doc(hidden)]
 pub use serde_json as _serde_json;
 
-use schema::{Schema, SchemaObject};
+use schema::Schema;
 
 /// A type which can be described as a JSON Schema document.
 ///
@@ -357,35 +361,16 @@ pub trait JsonSchema {
     /// This should not return a `$ref` schema.
     fn json_schema(gen: &mut gen::SchemaGenerator) -> Schema;
 
-    /// Helper for generating schemas for flattened `Option` fields.
-    ///
-    /// This should not need to be called or implemented by code outside of `schemars`,
-    /// and should not be considered part of the public API.
+    // TODO document and bring into public API?
     #[doc(hidden)]
-    fn json_schema_for_flatten(gen: &mut gen::SchemaGenerator) -> Schema {
+    fn _schemars_private_non_optional_json_schema(gen: &mut gen::SchemaGenerator) -> Schema {
         Self::json_schema(gen)
     }
 
-    /// Helper for generating schemas for `Option` fields.
-    ///
-    /// This should not need to be called or implemented by code outside of `schemars`,
-    /// and should not be considered part of the public API.
+    // TODO document and bring into public API?
     #[doc(hidden)]
-    fn add_schema_as_property(
-        gen: &mut gen::SchemaGenerator,
-        parent: &mut SchemaObject,
-        name: String,
-        metadata: Option<schema::Metadata>,
-        required: bool,
-    ) {
-        let mut schema = gen.subschema_for::<Self>();
-        schema = gen.apply_metadata(schema, metadata);
-
-        let object = parent.object();
-        if required {
-            object.required.insert(name.clone());
-        }
-        object.properties.insert(name, schema);
+    fn _schemars_private_is_option() -> bool {
+        false
     }
 }
 
diff --git a/schemars_derive/src/lib.rs b/schemars_derive/src/lib.rs
index 11e026f..d536488 100644
--- a/schemars_derive/src/lib.rs
+++ b/schemars_derive/src/lib.rs
@@ -70,18 +70,12 @@ fn derive_json_schema(
                         <#ty as schemars::JsonSchema>::json_schema(gen)
                     }
 
-                    fn json_schema_for_flatten(gen: &mut schemars::gen::SchemaGenerator) -> schemars::schema::Schema {
-                        <#ty as schemars::JsonSchema>::json_schema_for_flatten(gen)
+                    fn _schemars_private_non_optional_json_schema(gen: &mut schemars::gen::SchemaGenerator) -> schemars::schema::Schema {
+                        <#ty as schemars::JsonSchema>::_schemars_private_non_optional_json_schema(gen)
                     }
 
-                    fn add_schema_as_property(
-                        gen: &mut schemars::gen::SchemaGenerator,
-                        parent: &mut schemars::schema::SchemaObject,
-                        name: String,
-                        metadata: Option<schemars::schema::Metadata>,
-                        required: bool,
-                    ) {
-                        <#ty as schemars::JsonSchema>::add_schema_as_property(gen, parent, name, metadata, required)
+                    fn _schemars_private_is_option() -> bool {
+                        <#ty as schemars::JsonSchema>::_schemars_private_is_option()
                     }
                 };
             };
diff --git a/schemars_derive/src/metadata.rs b/schemars_derive/src/metadata.rs
index 435469a..a84deca 100644
--- a/schemars_derive/src/metadata.rs
+++ b/schemars_derive/src/metadata.rs
@@ -49,7 +49,7 @@ impl<'a> SchemaMetadata<'a> {
         quote! {
             {
                 let schema = #schema_expr;
-                gen.apply_metadata(schema, #self)
+                schemars::_private::apply_metadata(schema, #self)
             }
         }
     }
diff --git a/schemars_derive/src/schema_exprs.rs b/schemars_derive/src/schema_exprs.rs
index c5e83f2..f0f0c78 100644
--- a/schemars_derive/src/schema_exprs.rs
+++ b/schemars_derive/src/schema_exprs.rs
@@ -433,7 +433,7 @@ fn expr_for_struct(
             let args = quote!(gen, &mut schema_object, #name.to_owned(), #metadata, #required);
 
             quote_spanned! {ty.span()=>
-                <#ty as schemars::JsonSchema>::add_schema_as_property(#args);
+                schemars::_private::add_schema_as_property::<#ty>(#args);
             }
         })
         .collect();
@@ -448,7 +448,7 @@ fn expr_for_struct(
 
             let gen = quote!(gen);
             quote_spanned! {ty.span()=>
-                .flatten(<#ty as schemars::JsonSchema>::json_schema_for_flatten(#gen))
+                .flatten(schemars::_private::json_schema_for_flatten::<#ty>(#gen))
             }
         })
         .collect();