diff --git a/index.d.ts b/index.d.ts
index 7ffb68f..0ba9997 100644
--- a/index.d.ts
+++ b/index.d.ts
@@ -1 +1,3 @@
-export default function loadInitializers(app: object, prefix: string): void;
+import Engine from '@ember/engine';
+
+export default function loadInitializers(app: typeof Engine, prefix: string): void;
diff --git a/package.json b/package.json
index 6617a3c..bbdf49e 100644
--- a/package.json
+++ b/package.json
@@ -40,6 +40,7 @@
   },
   "devDependencies": {
     "@ember/optional-features": "^0.7.0",
+    "@types/ember__engine": "^3.0.4",
     "ember-cli": "~3.8.1",
     "ember-cli-dependency-checker": "^3.0.0",
     "ember-cli-eslint": "^4.2.3",
diff --git a/yarn.lock b/yarn.lock
index 892821e..42a5074 100644
--- a/yarn.lock
+++ b/yarn.lock
@@ -650,11 +650,32 @@
   resolved "https://registry.yarnpkg.com/@sindresorhus/is/-/is-0.7.0.tgz#9a06f4f137ee84d7df0460c1fdb1135ffa6c50fd"
   integrity sha512-ONhaKPIufzzrlNbqtWFFd+jlnemX6lJAgq9ZeiZtS7I1PIf/la7CW4m83rTXRnVnsMbW2k56pGYu7AUFJD9Pow==
 
+"@types/ember__engine@*", "@types/ember__engine@^3.0.4":
+  version "3.0.4"
+  resolved "https://registry.yarnpkg.com/@types/ember__engine/-/ember__engine-3.0.4.tgz#7e79d72653f5c7fd9f6d828d32540be372128aca"
+  integrity sha512-DfbM0iKgF8mvthZwshDgYn8H1BZQJOk42X5b183K7vbkaye49seeTnPDelrVRRnlMXH6BA6OHAghY92axwVLzw==
+  dependencies:
+    "@types/ember__engine" "*"
+    "@types/ember__object" "*"
+
+"@types/ember__object@*":
+  version "3.0.8"
+  resolved "https://registry.yarnpkg.com/@types/ember__object/-/ember__object-3.0.8.tgz#b62daeb8c86e377831c8320ba6dfaae9613bee8e"
+  integrity sha512-Rc6tQfFzXYJi7UtWrMd2ZZjlC3x2NI32UeqCwR/CxoH0pivmXStnjVDf/W3k601zRG0XYVUeDXpo8vb/Nhwfeg==
+  dependencies:
+    "@types/ember__object" "*"
+    "@types/rsvp" "*"
+
 "@types/node@*":
   version "10.12.0"
   resolved "https://registry.yarnpkg.com/@types/node/-/node-10.12.0.tgz#ea6dcbddbc5b584c83f06c60e82736d8fbb0c235"
   integrity sha512-3TUHC3jsBAB7qVRGxT6lWyYo2v96BMmD2PTcl47H25Lu7UXtFH/2qqmKiVrnel6Ne//0TFYf6uvNX+HW2FRkLQ==
 
+"@types/rsvp@*":
+  version "4.0.2"
+  resolved "https://registry.yarnpkg.com/@types/rsvp/-/rsvp-4.0.2.tgz#bf9f72eaa6771292638a85bb8ce1db97e754b371"
+  integrity sha512-48ZwxFD1hdBj8QMOSNGA2kYuo3+SKh8OEYh5cMi7cPRZXBF9jwVPV4yqA7EcJTNlAJL0v99pEUYetl0TsufMQA==
+
 abbrev@1:
   version "1.1.1"
   resolved "https://registry.yarnpkg.com/abbrev/-/abbrev-1.1.1.tgz#f8f2c887ad10bf67f634f005b6987fed3179aac8"
@@ -739,12 +760,7 @@ amdefine@>=0.0.4:
   resolved "https://registry.yarnpkg.com/amdefine/-/amdefine-1.0.1.tgz#4a5282ac164729e93619bcfd3ad151f817ce91f5"
   integrity sha1-SlKCrBZHKek2Gbz9OtFR+BfOkfU=
 
-ansi-escapes@^3.0.0:
-  version "3.1.0"
-  resolved "https://registry.yarnpkg.com/ansi-escapes/-/ansi-escapes-3.1.0.tgz#f73207bb81207d75fd6c83f125af26eea378ca30"
-  integrity sha512-UgAb8H9D41AQnu/PbWlCofQVcnV4Gs2bBJi9eZPxfU/hgglFh3SMDMENRIqdr7H6XFnXdoknctFByVsCOotTVw==
-
-ansi-escapes@^3.2.0:
+ansi-escapes@^3.0.0, ansi-escapes@^3.2.0:
   version "3.2.0"
   resolved "https://registry.yarnpkg.com/ansi-escapes/-/ansi-escapes-3.2.0.tgz#8780b98ff9dbf5638152d1f1fe5c1d7b4442976b"
   integrity sha512-cBhpre4ma+U0T1oM5fXg7Dy1Jw7zzwv7lt/GoCpr+hDQJoYnKVPLL4dCvSEFMmQurOQvSrwT7SL/DAlhBI97RQ==
@@ -2141,12 +2157,7 @@ can-symlink@^1.0.0:
   dependencies:
     tmp "0.0.28"
 
-caniuse-lite@^1.0.30000844:
-  version "1.0.30000899"
-  resolved "https://registry.yarnpkg.com/caniuse-lite/-/caniuse-lite-1.0.30000899.tgz#6febdbbc388a7982f620ee0e3d09aab0c061389e"
-  integrity sha512-enC3zKfUCJxxwvUIsBkbHd54CtJw1KtIWvrK0JZxWD/fEN2knHaai45lndJ4xXAkyRAPyk60J3yagkKDWhfeMA==
-
-caniuse-lite@^1.0.30000899:
+caniuse-lite@^1.0.30000844, caniuse-lite@^1.0.30000899:
   version "1.0.30000900"
   resolved "https://registry.yarnpkg.com/caniuse-lite/-/caniuse-lite-1.0.30000900.tgz#015cfe37897a3386a3075a914498800c29afe77e"
   integrity sha512-xDVs8pBFr6bzq9pXUkLKpGQQnzsF/l6/yX38UnCkTcUcwC0rDl1NGZGildcJVTU+uGBxfsyniK/ZWagPNn1Oqw==
@@ -3114,9 +3125,9 @@ ember-resolver@^5.1.3:
     resolve "^1.10.0"
 
 ember-rfc176-data@^0.3.5:
-  version "0.3.6"
-  resolved "https://registry.yarnpkg.com/ember-rfc176-data/-/ember-rfc176-data-0.3.6.tgz#7138db8dfccec39c9a832adfbd4c49d670028907"
-  integrity sha512-kPY94VCukPUPj+/6sZ9KvphD42KnpX2IS31p5z07OFVIviDogR0cQuld5c7Irzfgq7a0YACj0HlToROFn7dLYQ==
+  version "0.3.7"
+  resolved "https://registry.yarnpkg.com/ember-rfc176-data/-/ember-rfc176-data-0.3.7.tgz#ecff7d74987d09296d3703343fed934515a4be33"
+  integrity sha512-AbTlD+q7sfyrD4diZqE7r9Y9/Je+HntVn7TlpHAe+nP5BNXxUXJIfDs5w5e3MxPcMs6Dz/yY90YfW8h1oKEvGg==
 
 ember-rfc176-data@^0.3.8:
   version "0.3.8"
@@ -4064,7 +4075,7 @@ glob@^5.0.10:
     once "^1.3.0"
     path-is-absolute "^1.0.0"
 
-glob@^7.0.3, glob@^7.0.4, glob@^7.0.5, glob@^7.1.2, glob@^7.1.3:
+glob@^7.0.3, glob@^7.0.4, glob@^7.1.2, glob@^7.1.3:
   version "7.1.3"
   resolved "https://registry.yarnpkg.com/glob/-/glob-7.1.3.tgz#3960832d3f1574108342dafd3a67b332c0969df1"
   integrity sha512-vcfuiIxogLV4DlGBHIUOwI0IbrJ8HWPc4MU7HzviGeNho/UJDfi6B5p3sHeWIQ0KGIU0Jpxi5ZHxemQfLkkAwQ==
@@ -6675,14 +6686,7 @@ retry@^0.10.0:
   resolved "https://registry.yarnpkg.com/retry/-/retry-0.10.1.tgz#e76388d217992c252750241d3d3956fed98d8ff4"
   integrity sha1-52OI0heZLCUnUCQdPTlW/tmNj/Q=
 
-rimraf@^2.2.8, rimraf@^2.3.2, rimraf@^2.3.4, rimraf@^2.4.3, rimraf@^2.4.4, rimraf@^2.5.3, rimraf@^2.5.4, rimraf@^2.6.1, rimraf@^2.6.2:
-  version "2.6.2"
-  resolved "https://registry.yarnpkg.com/rimraf/-/rimraf-2.6.2.tgz#2ed8150d24a16ea8651e6d6ef0f47c4158ce7a36"
-  integrity sha512-lreewLK/BlghmxtfH36YYVg1i8IAce4TI7oao75I1g245+6BctqTVQiBP3YUJ9C6DQOXJmkYR9X9fCLtCOJc5w==
-  dependencies:
-    glob "^7.0.5"
-
-rimraf@~2.6.2:
+rimraf@^2.2.8, rimraf@^2.3.2, rimraf@^2.3.4, rimraf@^2.4.3, rimraf@^2.4.4, rimraf@^2.5.3, rimraf@^2.5.4, rimraf@^2.6.1, rimraf@^2.6.2, rimraf@~2.6.2:
   version "2.6.3"
   resolved "https://registry.yarnpkg.com/rimraf/-/rimraf-2.6.3.tgz#b2d104fe0d8fb27cf9e0a1cda8262dd3833c6cab"
   integrity sha512-mwqeW5XsA2qAejG46gYdENaxXjx9onRNCfn7L0duuP4hCuTIi/QO7PDK07KJfp1d+izWPrzEJDcSqBa0OZQriA==