diff --git a/langs/ts/ts.go b/langs/ts/ts.go
index 3d7e4c4..89ef720 100644
--- a/langs/ts/ts.go
+++ b/langs/ts/ts.go
@@ -23,9 +23,22 @@ func (m *Modeler) Model(schema *firemodel.Schema, sourceCoder firemodel.SourceCo
 	}
 	defer f.Close()
 
+	// d, err := os.Create("firebase.d.ts")
+	d, err := sourceCoder.NewFile("firebase.d.ts")
+	if err != nil {
+		return errors.Wrapf(err, "firemodel/ts: create typescript definition file")
+	}
+	defer d.Close()
+
 	if err := tpl.Execute(f, schema); err != nil {
 		return errors.Wrapf(err, "firemodel/ts: generating typescript")
 	}
+
+	_, err = d.Write([]byte(definitions))
+	if err != nil {
+		return errors.Wrapf(err, "firemodel/ts: writing typescript definitions")
+	}
+
 	return nil
 }
 
@@ -71,7 +84,7 @@ func toTypescriptType(firetype firemodel.SchemaFieldType) string {
 		return "firestore.Blob"
 	case *firemodel.Reference:
 		if firetype.T != nil {
-			return fmt.Sprintf("DocumentReference<%s>", interfaceName(firetype.T.Name))
+			return fmt.Sprintf("firestore.DocumentReference<%s>", interfaceName(firetype.T.Name))
 		} else {
 			return "firestore.DocumentReference"
 		}
@@ -137,128 +150,6 @@ const (
 	file = `// DO NOT EDIT - Code generated by firemodel {{firemodelVersion}}.
 import { firestore } from 'firebase';
 
-type Omit<T, K extends keyof T> = Pick<T, Exclude<keyof T, K>>;
-
-export interface Query<DataType = firestore.DocumentData>
-  extends firestore.Query {
-  where(
-    fieldPath: string | firestore.FieldPath,
-    opStr: firestore.WhereFilterOp,
-    value: any,
-  ): Query<DataType>;
-  orderBy(
-    fieldPath: string | firestore.FieldPath,
-    directionStr?: firestore.OrderByDirection,
-  ): Query<DataType>;
-  limit(limit: number): Query<DataType>;
-  startAt(snapshot: DocumentSnapshot): Query<DataType>;
-  startAt(...fieldValues: any[]): Query<DataType>;
-  startAfter(snapshot: DocumentSnapshot): Query<DataType>;
-  startAfter(...fieldValues: any[]): Query<DataType>;
-  endBefore(snapshot: DocumentSnapshot): Query<DataType>;
-  endBefore(...fieldValues: any[]): Query<DataType>;
-  endAt(snapshot: DocumentSnapshot): Query<DataType>;
-  endAt(...fieldValues: any[]): Query<DataType>;
-  get(options?: firestore.GetOptions): Promise<QuerySnapshot<DataType>>;
-  onSnapshot(observer: {
-    next?: (snapshot: QuerySnapshot<DataType>) => void;
-    error?: (error: Error) => void;
-    complete?: () => void;
-  }): () => void;
-  onSnapshot(
-    options: firestore.SnapshotListenOptions,
-    observer: {
-      next?: (snapshot: QuerySnapshot<DataType>) => void;
-      error?: (error: Error) => void;
-      complete?: () => void;
-    },
-  ): () => void;
-  onSnapshot(
-    onNext: (snapshot: QuerySnapshot<DataType>) => void,
-    onError?: (error: Error) => void,
-    onCompletion?: () => void,
-  ): () => void;
-  onSnapshot(
-    options: firestore.SnapshotListenOptions,
-    onNext: (snapshot: QuerySnapshot<DataType>) => void,
-    onError?: (error: Error) => void,
-    onCompletion?: () => void,
-  ): () => void;
-}
-
-
-export interface DocumentSnapshot<DataType = firestore.DocumentData>
-  extends firestore.DocumentSnapshot {
-  data(options?: firestore.SnapshotOptions): DataType | undefined;
-}
-export interface QueryDocumentSnapshot<DataType = firestore.DocumentData>
-  extends firestore.QueryDocumentSnapshot {
-  data(options?: firestore.SnapshotOptions): DataType | undefined;
-}
-export interface QuerySnapshot<DataType = firestore.DocumentData>
-  extends firestore.QuerySnapshot {
-  readonly docs: QueryDocumentSnapshot<DataType>[];
-}
-export interface DocumentSnapshotExpanded<DataType = firestore.DocumentData> {
-  exists: firestore.DocumentSnapshot['exists'];
-  ref: firestore.DocumentSnapshot['ref'];
-  id: firestore.DocumentSnapshot['id'];
-  metadata: firestore.DocumentSnapshot['metadata'];
-  data: DataType;
-}
-export interface QuerySnapshotExpanded<DataType = firestore.DocumentData> {
-  metadata: {
-    hasPendingWrites: firestore.QuerySnapshot['metadata']['hasPendingWrites'];
-    fromCache: firestore.QuerySnapshot['metadata']['fromCache'];
-  };
-  size: firestore.QuerySnapshot['size'];
-  empty: firestore.QuerySnapshot['empty'];
-  docs: {
-    [docId: string]: DocumentSnapshotExpanded<DataType>;
-  };
-}
-export interface DocumentReference<DataType = firestore.DocumentData>
-  extends firestore.DocumentReference {
-  set(data: DataType, options?: firestore.SetOptions): Promise<void>;
-  get(options?: firestore.GetOptions): Promise<DocumentSnapshot<DataType>>;
-  onSnapshot(observer: {
-    next?: (snapshot: DocumentSnapshot<DataType>) => void;
-    error?: (error: firestore.FirestoreError) => void;
-    complete?: () => void;
-  }): () => void;
-  onSnapshot(
-    options: firestore.SnapshotListenOptions,
-    observer: {
-      next?: (snapshot: DocumentSnapshot<DataType>) => void;
-      error?: (error: Error) => void;
-      complete?: () => void;
-    },
-  ): () => void;
-  onSnapshot(
-    onNext: (snapshot: DocumentSnapshot<DataType>) => void,
-    onError?: (error: Error) => void,
-    onCompletion?: () => void,
-  ): () => void;
-  onSnapshot(
-    options: firestore.SnapshotListenOptions,
-    onNext: (snapshot: DocumentSnapshot<DataType>) => void,
-    onError?: (error: Error) => void,
-    onCompletion?: () => void,
-  ): () => void;
-}
-
-
-
-export interface CollectionReference<DataType = firestore.DocumentData>
-  extends Query<DataType>,
-    Omit<firestore.CollectionReference, keyof Query> {
-  add(data: DataType): Promise<DocumentReference>;
-}
-export interface Collection<DataType = firestore.DocumentData> {
-  [id: string]: DocumentSnapshotExpanded<DataType>;
-}
-
-
 // tslint:disable-next-line:no-namespace
 export namespace {{.Options | getSchemaOption "ts" "namespace" "firemodel"}} {
   type URL = string;
@@ -295,7 +186,7 @@ export namespace {{.Options | getSchemaOption "ts" "namespace" "firemodel"}} {
     {{- else }}
     /** TODO: Add documentation to {{.Name}} in firemodel schema. */
     {{- end}}
-    {{.Name | ToLowerCamel}}: CollectionReference<{{.Type.Name | interfaceName | ToCamel}}>;
+    {{.Name | ToLowerCamel}}: firestore.CollectionReference<{{.Type.Name | interfaceName | ToCamel}}>;
     {{- end}}
 
     {{- range .Fields}}
@@ -352,4 +243,77 @@ export namespace {{.Options | getSchemaOption "ts" "namespace" "firemodel"}} {
     {{.Name}} = '{{.Name | ToScreamingSnake}}',
     {{- end}}
   }`
+
+	definitions = `import * as FIREBASE from 'firebase';
+
+declare module 'firebase' {
+  namespace firestore {
+    // Snapshots
+    export interface DocumentSnapshot<T = DocumentData> {
+      data(options?: SnapshotOptions): D | undefined;
+    }
+    export interface QueryDocumentSnapshot<T = DocumentData> extends DocumentSnapshot {
+      data(options?: SnapshotOptions): T;
+    }
+    export interface QuerySnapshot<T = DocumentData> {
+      readonly docs: QueryDocumentSnapshot<T>[];
+      forEach(callback: (result: QueryDocumentSnapshot<T>) => void, thisArg?: any): void;
+    }
+
+    // References + Queries
+    export interface DocumentReference<T = DocumentData> {
+      onSnapshot(observer: {
+        next?: (snapshot: DocumentSnapshot<T>) => void;
+        error?: (error: FirestoreError) => void;
+        complete?: () => void;
+      }): () => void;
+      onSnapshot(
+        options: SnapshotListenOptions,
+        observer: {
+          next?: (snapshot: DocumentSnapshot<T>) => void;
+          error?: (error: Error) => void;
+          complete?: () => void;
+        },
+      ): () => void;
+      onSnapshot(
+        onNext: (snapshot: DocumentSnapshot<T>) => void,
+        onError?: (error: Error) => void,
+        onCompletion?: () => void,
+      ): () => void;
+      onSnapshot(
+        options: SnapshotListenOptions,
+        onNext: (snapshot: DocumentSnapshot<T>) => void,
+        onError?: (error: Error) => void,
+        onCompletion?: () => void,
+      ): () => void;
+    }
+    export interface Query<T = DocumentData> {
+      onSnapshot(observer: {
+        next?: (snapshot: QuerySnapshot<T>) => void;
+        error?: (error: Error) => void;
+        complete?: () => void;
+      }): () => void;
+      onSnapshot(
+        options: SnapshotListenOptions,
+        observer: {
+          next?: (snapshot: QuerySnapshot<T>) => void;
+          error?: (error: Error) => void;
+          complete?: () => void;
+        },
+      ): () => void;
+      onSnapshot(
+        onNext: (snapshot: QuerySnapshot<T>) => void,
+        onError?: (error: Error) => void,
+        onCompletion?: () => void,
+      ): () => void;
+      onSnapshot(
+        options: SnapshotListenOptions,
+        onNext: (snapshot: QuerySnapshot<T>) => void,
+        onError?: (error: Error) => void,
+        onCompletion?: () => void,
+      ): () => void;
+    }
+    export interface CollectionReference<T = DocumentData> extends Query<T> {}
+  }
+}`
 )
diff --git a/testfixtures/firemodel/TestFiremodelFromSchema/ts/firebase.d.ts b/testfixtures/firemodel/TestFiremodelFromSchema/ts/firebase.d.ts
new file mode 100644
index 0000000..f796807
--- /dev/null
+++ b/testfixtures/firemodel/TestFiremodelFromSchema/ts/firebase.d.ts
@@ -0,0 +1,72 @@
+import * as FIREBASE from 'firebase';
+
+declare module 'firebase' {
+  namespace firestore {
+    // Snapshots
+    export interface DocumentSnapshot<T = DocumentData> {
+      data(options?: SnapshotOptions): D | undefined;
+    }
+    export interface QueryDocumentSnapshot<T = DocumentData> extends DocumentSnapshot {
+      data(options?: SnapshotOptions): T;
+    }
+    export interface QuerySnapshot<T = DocumentData> {
+      readonly docs: QueryDocumentSnapshot<T>[];
+      forEach(callback: (result: QueryDocumentSnapshot<T>) => void, thisArg?: any): void;
+    }
+
+    // References + Queries
+    export interface DocumentReference<T = DocumentData> {
+      onSnapshot(observer: {
+        next?: (snapshot: DocumentSnapshot<T>) => void;
+        error?: (error: FirestoreError) => void;
+        complete?: () => void;
+      }): () => void;
+      onSnapshot(
+        options: SnapshotListenOptions,
+        observer: {
+          next?: (snapshot: DocumentSnapshot<T>) => void;
+          error?: (error: Error) => void;
+          complete?: () => void;
+        },
+      ): () => void;
+      onSnapshot(
+        onNext: (snapshot: DocumentSnapshot<T>) => void,
+        onError?: (error: Error) => void,
+        onCompletion?: () => void,
+      ): () => void;
+      onSnapshot(
+        options: SnapshotListenOptions,
+        onNext: (snapshot: DocumentSnapshot<T>) => void,
+        onError?: (error: Error) => void,
+        onCompletion?: () => void,
+      ): () => void;
+    }
+    export interface Query<T = DocumentData> {
+      onSnapshot(observer: {
+        next?: (snapshot: QuerySnapshot<T>) => void;
+        error?: (error: Error) => void;
+        complete?: () => void;
+      }): () => void;
+      onSnapshot(
+        options: SnapshotListenOptions,
+        observer: {
+          next?: (snapshot: QuerySnapshot<T>) => void;
+          error?: (error: Error) => void;
+          complete?: () => void;
+        },
+      ): () => void;
+      onSnapshot(
+        onNext: (snapshot: QuerySnapshot<T>) => void,
+        onError?: (error: Error) => void,
+        onCompletion?: () => void,
+      ): () => void;
+      onSnapshot(
+        options: SnapshotListenOptions,
+        onNext: (snapshot: QuerySnapshot<T>) => void,
+        onError?: (error: Error) => void,
+        onCompletion?: () => void,
+      ): () => void;
+    }
+    export interface CollectionReference<T = DocumentData> extends Query<T> {}
+  }
+}
\ No newline at end of file
diff --git a/testfixtures/firemodel/TestFiremodelFromSchema/ts/firemodel.ts b/testfixtures/firemodel/TestFiremodelFromSchema/ts/firemodel.ts
index 786dd82..920fab2 100644
--- a/testfixtures/firemodel/TestFiremodelFromSchema/ts/firemodel.ts
+++ b/testfixtures/firemodel/TestFiremodelFromSchema/ts/firemodel.ts
@@ -1,128 +1,6 @@
 // DO NOT EDIT - Code generated by firemodel (dev).
 import { firestore } from 'firebase';
 
-type Omit<T, K extends keyof T> = Pick<T, Exclude<keyof T, K>>;
-
-export interface Query<DataType = firestore.DocumentData>
-  extends firestore.Query {
-  where(
-    fieldPath: string | firestore.FieldPath,
-    opStr: firestore.WhereFilterOp,
-    value: any,
-  ): Query<DataType>;
-  orderBy(
-    fieldPath: string | firestore.FieldPath,
-    directionStr?: firestore.OrderByDirection,
-  ): Query<DataType>;
-  limit(limit: number): Query<DataType>;
-  startAt(snapshot: DocumentSnapshot): Query<DataType>;
-  startAt(...fieldValues: any[]): Query<DataType>;
-  startAfter(snapshot: DocumentSnapshot): Query<DataType>;
-  startAfter(...fieldValues: any[]): Query<DataType>;
-  endBefore(snapshot: DocumentSnapshot): Query<DataType>;
-  endBefore(...fieldValues: any[]): Query<DataType>;
-  endAt(snapshot: DocumentSnapshot): Query<DataType>;
-  endAt(...fieldValues: any[]): Query<DataType>;
-  get(options?: firestore.GetOptions): Promise<QuerySnapshot<DataType>>;
-  onSnapshot(observer: {
-    next?: (snapshot: QuerySnapshot<DataType>) => void;
-    error?: (error: Error) => void;
-    complete?: () => void;
-  }): () => void;
-  onSnapshot(
-    options: firestore.SnapshotListenOptions,
-    observer: {
-      next?: (snapshot: QuerySnapshot<DataType>) => void;
-      error?: (error: Error) => void;
-      complete?: () => void;
-    },
-  ): () => void;
-  onSnapshot(
-    onNext: (snapshot: QuerySnapshot<DataType>) => void,
-    onError?: (error: Error) => void,
-    onCompletion?: () => void,
-  ): () => void;
-  onSnapshot(
-    options: firestore.SnapshotListenOptions,
-    onNext: (snapshot: QuerySnapshot<DataType>) => void,
-    onError?: (error: Error) => void,
-    onCompletion?: () => void,
-  ): () => void;
-}
-
-
-export interface DocumentSnapshot<DataType = firestore.DocumentData>
-  extends firestore.DocumentSnapshot {
-  data(options?: firestore.SnapshotOptions): DataType | undefined;
-}
-export interface QueryDocumentSnapshot<DataType = firestore.DocumentData>
-  extends firestore.QueryDocumentSnapshot {
-  data(options?: firestore.SnapshotOptions): DataType | undefined;
-}
-export interface QuerySnapshot<DataType = firestore.DocumentData>
-  extends firestore.QuerySnapshot {
-  readonly docs: QueryDocumentSnapshot<DataType>[];
-}
-export interface DocumentSnapshotExpanded<DataType = firestore.DocumentData> {
-  exists: firestore.DocumentSnapshot['exists'];
-  ref: firestore.DocumentSnapshot['ref'];
-  id: firestore.DocumentSnapshot['id'];
-  metadata: firestore.DocumentSnapshot['metadata'];
-  data: DataType;
-}
-export interface QuerySnapshotExpanded<DataType = firestore.DocumentData> {
-  metadata: {
-    hasPendingWrites: firestore.QuerySnapshot['metadata']['hasPendingWrites'];
-    fromCache: firestore.QuerySnapshot['metadata']['fromCache'];
-  };
-  size: firestore.QuerySnapshot['size'];
-  empty: firestore.QuerySnapshot['empty'];
-  docs: {
-    [docId: string]: DocumentSnapshotExpanded<DataType>;
-  };
-}
-export interface DocumentReference<DataType = firestore.DocumentData>
-  extends firestore.DocumentReference {
-  set(data: DataType, options?: firestore.SetOptions): Promise<void>;
-  get(options?: firestore.GetOptions): Promise<DocumentSnapshot<DataType>>;
-  onSnapshot(observer: {
-    next?: (snapshot: DocumentSnapshot<DataType>) => void;
-    error?: (error: firestore.FirestoreError) => void;
-    complete?: () => void;
-  }): () => void;
-  onSnapshot(
-    options: firestore.SnapshotListenOptions,
-    observer: {
-      next?: (snapshot: DocumentSnapshot<DataType>) => void;
-      error?: (error: Error) => void;
-      complete?: () => void;
-    },
-  ): () => void;
-  onSnapshot(
-    onNext: (snapshot: DocumentSnapshot<DataType>) => void,
-    onError?: (error: Error) => void,
-    onCompletion?: () => void,
-  ): () => void;
-  onSnapshot(
-    options: firestore.SnapshotListenOptions,
-    onNext: (snapshot: DocumentSnapshot<DataType>) => void,
-    onError?: (error: Error) => void,
-    onCompletion?: () => void,
-  ): () => void;
-}
-
-
-
-export interface CollectionReference<DataType = firestore.DocumentData>
-  extends Query<DataType>,
-    Omit<firestore.CollectionReference, keyof Query> {
-  add(data: DataType): Promise<DocumentReference>;
-}
-export interface Collection<DataType = firestore.DocumentData> {
-  [id: string]: DocumentSnapshotExpanded<DataType>;
-}
-
-
 // tslint:disable-next-line:no-namespace
 export namespace example {
   type URL = string;
@@ -158,7 +36,7 @@ export namespace example {
   /** A Test is a test model. */
   export interface ITestModel {
     /** TODO: Add documentation to nested_collection in firemodel schema. */
-    nestedCollection: CollectionReference<ITestModel>;
+    nestedCollection: firestore.CollectionReference<ITestModel>;
     /** The name. */
     name?: string;
     /** The age. */
@@ -172,7 +50,7 @@ export namespace example {
     /** TODO: Add documentation to data in firemodel schema. */
     data?: firestore.Blob;
     /** TODO: Add documentation to friend in firemodel schema. */
-    friend?: DocumentReference<ITestModel>;
+    friend?: firestore.DocumentReference<ITestModel>;
     /** TODO: Add documentation to location in firemodel schema. */
     location?: firestore.GeoPoint;
     /** TODO: Add documentation to colors in firemodel schema. */
@@ -192,7 +70,7 @@ export namespace example {
     /** TODO: Add documentation to refs in firemodel schema. */
     refs?: firestore.DocumentReference[];
     /** TODO: Add documentation to model_refs in firemodel schema. */
-    modelRefs?: DocumentReference<ITestTimestamps>[];
+    modelRefs?: firestore.DocumentReference<ITestTimestamps>[];
     /** TODO: Add documentation to meta in firemodel schema. */
     meta?: { [key: string]: any; };
     /** TODO: Add documentation to meta_strs in firemodel schema. */