diff --git a/schemars/src/main.rs b/schemars/src/main.rs
index b5feaf0..ec8cfc4 100644
--- a/schemars/src/main.rs
+++ b/schemars/src/main.rs
@@ -6,7 +6,6 @@ use make_schema::MakeSchema;
 use schema::*;
 use serde::{Deserialize, Serialize};
 use serde_json::Result;
-use std::collections::BTreeMap as Map;
 
 #[derive(Serialize, Deserialize, Debug)]
 #[serde(rename_all = "camelCase")]
@@ -34,10 +33,27 @@ struct User {
     username: String,
 }
 
+impl MakeSchema for User {
+    fn generates_ref_schema() -> bool {
+        true
+    }
+
+    fn make_schema(gen: &mut generator::SchemaGenerator) -> Schema {
+        let mut o = SchemaObject {
+            ..Default::default()
+        };
+        o.properties
+            .insert("id".to_owned(), gen.subschema_for::<u64>());
+        o.properties
+            .insert("username".to_owned(), gen.subschema_for::<String>());
+        o.into()
+    }
+}
+
 fn main() -> Result<()> {
     let gen = generator::SchemaGenerator::new();
-    let schema = gen.into_root_schema_for::<str>();
-    let json = serde_json::to_string(&schema)?;
+    let schema = gen.into_root_schema_for::<User>();
+    let json = serde_json::to_string_pretty(&schema)?;
     println!("{}", json);
 
     /*let todo = Todo {
diff --git a/schemars/src/make_schema.rs b/schemars/src/make_schema.rs
index db78ede..1c7d986 100644
--- a/schemars/src/make_schema.rs
+++ b/schemars/src/make_schema.rs
@@ -26,7 +26,7 @@ pub trait MakeSchema {
         false
     }
 
-    fn make_schema(generator: &mut SchemaGenerator) -> Schema;
+    fn make_schema(gen: &mut SchemaGenerator) -> Schema;
 }
 
 // TODO structs, enums, tuples
@@ -76,12 +76,12 @@ simple_impl!(() => Null);
 
 impl MakeSchema for char {
     fn make_schema(_: &mut SchemaGenerator) -> Schema {
-        let mut extra_properties = Map::new();
-        extra_properties.insert("minLength".to_owned(), json!(1));
-        extra_properties.insert("maxLength".to_owned(), json!(1));
+        let mut extensions = Map::new();
+        extensions.insert("minLength".to_owned(), json!(1));
+        extensions.insert("maxLength".to_owned(), json!(1));
         SchemaObject {
             instance_type: Some(InstanceType::String.into()),
-            extra_properties,
+            extensions,
             ..Default::default()
         }
         .into()
@@ -93,11 +93,11 @@ impl MakeSchema for char {
 // Does not require T: MakeSchema.
 impl<T> MakeSchema for [T; 0] {
     fn make_schema(_: &mut SchemaGenerator) -> Schema {
-        let mut extra_properties = Map::new();
-        extra_properties.insert("maxItems".to_owned(), json!(0));
+        let mut extensions = Map::new();
+        extensions.insert("maxItems".to_owned(), json!(0));
         SchemaObject {
             instance_type: Some(InstanceType::Array.into()),
-            extra_properties,
+            extensions,
             ..Default::default()
         }
         .into()
@@ -110,13 +110,13 @@ macro_rules! array_impls {
             impl<T: MakeSchema> MakeSchema for [T; $len]
             {
                 fn make_schema(gen: &mut SchemaGenerator) -> Schema {
-                    let mut extra_properties = Map::new();
-                    extra_properties.insert("minItems".to_owned(), json!($len));
-                    extra_properties.insert("maxItems".to_owned(), json!($len));
+                    let mut extensions = Map::new();
+                    extensions.insert("minItems".to_owned(), json!($len));
+                    extensions.insert("maxItems".to_owned(), json!($len));
                     SchemaObject {
                         instance_type: Some(InstanceType::Array.into()),
                         items: Some(Box::from(gen.subschema_for::<T>())),
-                        extra_properties,
+                        extensions,
                         ..Default::default()
                     }.into()
                 }
@@ -170,14 +170,14 @@ macro_rules! map_impl {
         {
             fn make_schema(gen: &mut SchemaGenerator) -> Schema
             {
-                let mut extra_properties = Map::new();
-                extra_properties.insert(
+                let mut extensions = Map::new();
+                extensions.insert(
                     "additionalProperties".to_owned(),
                     json!(gen.subschema_for::<T>())
                 );
                 SchemaObject {
                     instance_type: Some(InstanceType::Object.into()),
-                    extra_properties,
+                    extensions,
                     ..Default::default()
                 }.into()
             }
diff --git a/schemars/src/schema.rs b/schemars/src/schema.rs
index 68ec599..2ac72c0 100644
--- a/schemars/src/schema.rs
+++ b/schemars/src/schema.rs
@@ -66,7 +66,7 @@ pub struct SchemaObject {
     #[serde(skip_serializing_if = "Map::is_empty")]
     pub definitions: Map<String, Schema>,
     #[serde(flatten)]
-    pub extra_properties: Map<String, Value>,
+    pub extensions: Map<String, Value>,
 }
 
 #[derive(Serialize, Deserialize, Debug, Clone, PartialEq)]