diff --git a/Sources/MongoDriver/MongoDriver.swift b/Sources/MongoDriver/MongoDriver.swift
index d3364a3..f8af598 100644
--- a/Sources/MongoDriver/MongoDriver.swift
+++ b/Sources/MongoDriver/MongoDriver.swift
@@ -264,7 +264,7 @@ extension MongoKitten.Database : Fluent.Driver, Connection {
             let collectionName = lookup.joined.name
 
             pipeline.append(.lookup(from: self[lookup.joined.entity], localField: lookup.baseKey, foreignField: lookup.joinedKey, as: collectionName))
-            pipeline.append(.unwind("$" + collectionName))
+            pipeline.append(.unwind("$" + collectionName, preserveNullAndEmptyArrays: lookup.kind == .outer))
         }
 
         pipeline.append(.match(filter))
diff --git a/Tests/MongoDriverTests/DriverTests.swift b/Tests/MongoDriverTests/DriverTests.swift
index 343a7cc..540d509 100755
--- a/Tests/MongoDriverTests/DriverTests.swift
+++ b/Tests/MongoDriverTests/DriverTests.swift
@@ -8,6 +8,7 @@ class DriverTests: XCTestCase {
         return [
             ("testInsertAndFind", testInsertAndFind),
             ("testArray", testArray),
+            ("testOuterJoin", testOuterJoin),
             ("testSiblingsCount", testSiblingsCount),
             ("testMax", testMax),
             ("testSiblingsMax", testSiblingsMax),
@@ -61,6 +62,49 @@ class DriverTests: XCTestCase {
         XCTAssert(foundStore.vinyls.filter({ return $0.name == "Thriller" }).count == 1)
     }
 
+    func testOuterJoin() throws {
+        try driver.drop()
+        let db = Fluent.Database(driver)
+
+        Pet.database = db
+        Toy.database = db
+
+        let ball = Toy(name: "ball")
+        let bone = Toy(name: "bone")
+        let puppet = Toy(name: "puppet")
+
+        try ball.save()
+        try bone.save()
+        try puppet.save()
+
+        let molly = Pet(name: "Molly", age: 2)
+        molly.favoriteToyId = ball.id
+
+        let rex = Pet(name: "Rex", age: 1)
+
+        try molly.save()
+        try rex.save()
+
+        XCTAssertNotNil(try molly.favoriteToy.get())
+        XCTAssertNil(try rex.favoriteToy.get())
+
+        let toysFavoritedByPets = try Toy.makeQuery()
+            .join(kind: .inner, Pet.self, baseKey: Toy.idKey, joinedKey: "favoriteToyId")
+            .all()
+
+        XCTAssertEqual(toysFavoritedByPets.count, 1)
+        XCTAssertEqual(toysFavoritedByPets.first?.id, ball.id)
+
+        let toysNotFavoritedByPets = try Toy.makeQuery()
+            .join(kind: .outer, Pet.self, baseKey: Toy.idKey, joinedKey: "favoriteToyId")
+            .filter(Pet.self, Pet.idKey, .equals, nil)
+            .all()
+
+        XCTAssertEqual(toysNotFavoritedByPets.count, 2)
+        XCTAssertTrue(toysNotFavoritedByPets.contains(where: { $0.id == bone.id }))
+        XCTAssertTrue(toysNotFavoritedByPets.contains(where: { $0.id == puppet.id }))
+    }
+
     func testSiblingsCount() throws {
         try driver.drop()
         let db = Fluent.Database(driver)
diff --git a/Tests/MongoDriverTests/Pet.swift b/Tests/MongoDriverTests/Pet.swift
index dc0e82a..f4fdd59 100644
--- a/Tests/MongoDriverTests/Pet.swift
+++ b/Tests/MongoDriverTests/Pet.swift
@@ -14,9 +14,12 @@ final class Pet: Entity {
 
     public let age: Int
 
-    public init(name: String, age: Int) {
+    public var favoriteToyId: Identifier?
+
+    public init(name: String, age: Int, favoriteToyId: Identifier? = nil) {
         self.name = name
         self.age = age
+        self.favoriteToyId = favoriteToyId
     }
 
     // MARK: Storable
@@ -27,7 +30,11 @@ final class Pet: Entity {
 
     public convenience init(row: Row) throws {
 
-        self.init(name: try row.get("name"), age: try row.get("age"))
+        self.init(
+            name: try row.get("name"),
+            age: try row.get("age"),
+            favoriteToyId: try row.get("favoriteToyId")
+        )
     }
 
     public func makeRow() throws -> Row {
@@ -37,6 +44,7 @@ final class Pet: Entity {
         try row.set(Pet.idKey, self.id)
         try row.set("name", self.name)
         try row.set("age", self.age)
+        try row.set("favoriteToyId", self.favoriteToyId)
 
         return row
     }
@@ -46,6 +54,10 @@ final class Pet: Entity {
 
 extension Pet {
 
+    public var favoriteToy: Parent<Pet, Toy> {
+        return self.parent(id: self.favoriteToyId)
+    }
+
     public var toys: Siblings<Pet, Toy, Pivot<Pet, Toy>> {
         return self.siblings()
     }