diff --git a/datafiles/managers.py b/datafiles/managers.py
index 60cd6298..6e8023ea 100644
--- a/datafiles/managers.py
+++ b/datafiles/managers.py
@@ -5,6 +5,7 @@
 import os
 from pathlib import Path
 from typing import Any, Dict, Optional
+from typing_extensions import Protocol
 
 import log
 from cached_property import cached_property
@@ -18,35 +19,6 @@
 Missing = dataclasses._MISSING_TYPE
 
 
-class Manager:
-    def __init__(self, cls):
-        self.model = cls
-
-    def all(self):
-        raise NotImplementedError
-
-    def get_or_none(self, *args, **kwargs):
-        original_manual = self.model.Meta.datafile_manual
-
-        self.model.Meta.datafile_manual = True
-        instance = self.model(*args, **kwargs)
-        self.model.Meta.datafile_manual = original_manual
-
-        if instance.datafile.exists:
-            instance.datafile._manual = original_manual
-            return instance
-
-        return None
-
-    def get_or_create(self, *args, **kwargs):
-        instance = self.model(*args, **kwargs)
-
-        if not instance.datafile.exists:
-            instance.datafile.save()
-
-        return instance
-
-
 class Datafile:
     def __init__(
         self,
@@ -368,3 +340,37 @@ def _write(self, text: str):
         log.debug('=' * len(message) + '\n\n' + (text or '<nothing>\n'))
         self.path.parent.mkdir(parents=True, exist_ok=True)
         self.path.write_text(text)
+
+
+class HasDatafile(Protocol):
+
+    datafile: Datafile
+
+
+class Manager:
+    def __init__(self, cls):
+        self.model = cls
+
+    def all(self):
+        raise NotImplementedError
+
+    def get_or_none(self, *args, **kwargs) -> Optional[HasDatafile]:
+        original_manual = self.model.Meta.datafile_manual
+
+        self.model.Meta.datafile_manual = True
+        instance = self.model(*args, **kwargs)
+        self.model.Meta.datafile_manual = original_manual
+
+        if instance.datafile.exists:
+            instance.datafile._manual = original_manual
+            return instance
+
+        return None
+
+    def get_or_create(self, *args, **kwargs) -> HasDatafile:
+        instance = self.model(*args, **kwargs)
+
+        if not instance.datafile.exists:
+            instance.datafile.save()
+
+        return instance
diff --git a/poetry.lock b/poetry.lock
index 9a4a3be4..984fe329 100644
--- a/poetry.lock
+++ b/poetry.lock
@@ -382,7 +382,7 @@ description = "A fast and thorough lazy object proxy."
 name = "lazy-object-proxy"
 optional = false
 python-versions = ">=2.7, !=3.0.*, !=3.1.*, !=3.2.*, !=3.3.*"
-version = "1.4.0"
+version = "1.4.1"
 
 [[package]]
 category = "dev"
@@ -671,7 +671,7 @@ description = "Persistent/Functional/Immutable data structures"
 name = "pyrsistent"
 optional = false
 python-versions = "*"
-version = "0.15.1"
+version = "0.15.2"
 
 [package.dependencies]
 six = "*"
@@ -682,16 +682,17 @@ description = "pytest: simple powerful testing with Python"
 name = "pytest"
 optional = false
 python-versions = ">=2.7, !=3.0.*, !=3.1.*, !=3.2.*, !=3.3.*"
-version = "4.4.2"
+version = "4.5.0"
 
 [package.dependencies]
 atomicwrites = ">=1.0"
 attrs = ">=17.4.0"
 colorama = "*"
-pluggy = ">=0.11"
+pluggy = ">=0.9,<0.10 || >0.10,<1.0"
 py = ">=1.5.0"
 setuptools = "*"
 six = ">=1.10.0"
+wcwidth = "*"
 
 [package.dependencies.more-itertools]
 python = ">=2.8"
@@ -813,7 +814,7 @@ category = "dev"
 description = "YAML parser and emitter for Python"
 name = "pyyaml"
 optional = false
-python-versions = "*"
+python-versions = ">=2.7, !=3.0.*, !=3.1.*, !=3.2.*, !=3.3.*"
 version = "5.1"
 
 [[package]]
@@ -952,6 +953,25 @@ optional = false
 python-versions = "*"
 version = "1.3.5"
 
+[[package]]
+category = "main"
+description = "Type Hints for Python"
+name = "typing"
+optional = false
+python-versions = "*"
+version = "3.6.6"
+
+[[package]]
+category = "main"
+description = "Backported and Experimental Type Hints for Python 3.5+"
+name = "typing-extensions"
+optional = false
+python-versions = "*"
+version = "3.7.2"
+
+[package.dependencies]
+typing = ">=3.6.2"
+
 [[package]]
 category = "dev"
 description = "HTTP library with thread-safe connection pooling, file post, and more."
@@ -1009,7 +1029,7 @@ python-versions = "*"
 version = "1.11.1"
 
 [metadata]
-content-hash = "9bc530fda4e68ee95fb8595b0a7e60d4bf59c1db84019b74b83a94d3af514bae"
+content-hash = "f24dab983648540a12a567618a6b80486607b48c8e5420a64576b5d84c5a09e6"
 python-versions = "^3.7"
 
 [metadata.hashes]
@@ -1049,7 +1069,7 @@ jupyter = ["3e1f86076bbb7c8c207829390305a2b1fe836d471ed54be66a3b8c41e7f46cc7", "
 jupyter-client = ["b5f9cb06105c1d2d30719db5ffb3ea67da60919fb68deaefa583deccd8813551", "c44411eb1463ed77548bc2d5ec0d744c9b81c4a542d9637c7a52824e2121b987"]
 jupyter-console = ["308ce876354924fb6c540b41d5d6d08acfc946984bf0c97777c1ddcb42e0b2f5", "cc80a97a5c389cbd30252ffb5ce7cefd4b66bde98219edd16bf5cb6f84bb3568"]
 jupyter-core = ["927d713ffa616ea11972534411544589976b2493fc7e09ad946e010aa7eb9970", "ba70754aa680300306c699790128f6fbd8c306ee5927976cbe48adacf240c0b7"]
-lazy-object-proxy = ["118d53f8819f9457732dd0e418752f2850f395c5405b2e12485f52336e4ad0f5", "495c583b363c3eded649e2c00177093f03f856f5c9f95b527420084a9ce17b9d", "55fa9eab93482891ce97473e63610efdd9c8fa5c05cca9f60468c412e602e499", "642fc0a9b61920669dab66e400f79f1b8b0e8f698dcde85f7e9ae5528dbcaf4a", "7003959a170fde9b92936c38562810f94679c80608fb4b007e026b915bef8b27", "7e63da94f5a1ddb0d2dcdb5d17ff4d1d33f51f3368bdf0475d5f56c0f3b99592", "7fb11d33d99a374e4b0c3fb20128890b9cf784ca7e4b91ecbb191d34618bd9fe", "8758715ea005afa293783797498d64f40ab14d1ded208b3e282760cde9512f1d", "8995543f47a8b81962e384f12791114af9f4997be7a0db71abc40d2a2dfee961", "91c7e1316116fedda36818ce7cd269378fffc4219781536eff441ea1e68e1caf", "9b41ec246d31ca6a840dcf67673b2668adc5a095c64310d26d73292588563ea3", "a8be3cfd7c3154e8d39276c627c5e7ee55d1f2094597b060ece99620ef9fe86b", "afcab74f471652b643900e0862b31892ac5fe5a75e435b786a1825855f4effdf", "d49a90c27074f44c8dc147d83e31140523948ee147b3248634c540e053caea58", "d6957cadc9c079ef4697564af500d52fba6d14fb2f08d20ce92f52201fb77050", "da7f2a6c82a11dc4e05bab73522f0d6dd4f3bbc8378cd4b0769137f342cdb3f0", "f03a21f6f6e54778860122a620f70c8b148ec4ee175968782bcaaa94955a46f9", "f6c718ffca055852479880debbe717da952fcfd60067a0ddb6fe3b053b1d4de0"]
+lazy-object-proxy = ["159a745e61422217881c4de71f9eafd9d703b93af95618635849fe469a283661", "23f63c0821cc96a23332e45dfaa83266feff8adc72b9bcaef86c202af765244f", "3b11be575475db2e8a6e11215f5aa95b9ec14de658628776e10d96fa0b4dac13", "3f447aff8bc61ca8b42b73304f6a44fa0d915487de144652816f950a3f1ab821", "4ba73f6089cd9b9478bc0a4fa807b47dbdb8fad1d8f31a0f0a5dbf26a4527a71", "4f53eadd9932055eac465bd3ca1bd610e4d7141e1278012bd1f28646aebc1d0e", "64483bd7154580158ea90de5b8e5e6fc29a16a9b4db24f10193f0c1ae3f9d1ea", "6f72d42b0d04bfee2397aa1862262654b56922c20a9bb66bb76b6f0e5e4f9229", "7c7f1ec07b227bdc561299fa2328e85000f90179a2f44ea30579d38e037cb3d4", "7c8b1ba1e15c10b13cad4171cfa77f5bb5ec2580abc5a353907780805ebe158e", "8559b94b823f85342e10d3d9ca4ba5478168e1ac5658a8a2f18c991ba9c52c20", "a262c7dfb046f00e12a2bdd1bafaed2408114a89ac414b0af8755c696eb3fc16", "acce4e3267610c4fdb6632b3886fe3f2f7dd641158a843cf6b6a68e4ce81477b", "be089bb6b83fac7f29d357b2dc4cf2b8eb8d98fe9d9ff89f9ea6012970a853c7", "bfab710d859c779f273cc48fb86af38d6e9210f38287df0069a63e40b45a2f5c", "c10d29019927301d524a22ced72706380de7cfc50f767217485a912b4c8bd82a", "dd6e2b598849b3d7aee2295ac765a578879830fb8966f70be8cd472e6069932e", "e408f1eacc0a68fed0c08da45f31d0ebb38079f043328dce69ff133b95c29dc1"]
 livereload = ["78d55f2c268a8823ba499305dcac64e28ddeb9a92571e12d543cd304faf5817b", "89254f78d7529d7ea0a3417d224c34287ebfe266b05e67e51facaf82c27f0f66"]
 markdown = ["fc4a6f69a656b8d858d7503bda633f4dd63c2d70cf80abdc6eafa64c4ae8c250", "fe463ff51e679377e3624984c829022e2cfb3be5518726b06f608a07a3aad680"]
 markupsafe = ["00bc623926325b26bb9605ae9eae8a215691f33cae5df11ca5424f06f2d1f473", "09027a7803a62ca78792ad89403b1b7a73a01c8cb65909cd876f7fcebd79b161", "09c4b7f37d6c648cb13f9230d847adf22f8171b1ccc4d5682398e77f40309235", "1027c282dad077d0bae18be6794e6b6b8c91d58ed8a8d89a89d59693b9131db5", "24982cc2533820871eba85ba648cd53d8623687ff11cbb805be4ff7b4c971aff", "29872e92839765e546828bb7754a68c418d927cd064fd4708fab9fe9c8bb116b", "43a55c2930bbc139570ac2452adf3d70cdbb3cfe5912c71cdce1c2c6bbd9c5d1", "46c99d2de99945ec5cb54f23c8cd5689f6d7177305ebff350a58ce5f8de1669e", "500d4957e52ddc3351cabf489e79c91c17f6e0899158447047588650b5e69183", "535f6fc4d397c1563d08b88e485c3496cf5784e927af890fb3c3aac7f933ec66", "62fe6c95e3ec8a7fad637b7f3d372c15ec1caa01ab47926cfdf7a75b40e0eac1", "6dd73240d2af64df90aa7c4e7481e23825ea70af4b4922f8ede5b9e35f78a3b1", "717ba8fe3ae9cc0006d7c451f0bb265ee07739daf76355d06366154ee68d221e", "79855e1c5b8da654cf486b830bd42c06e8780cea587384cf6545b7d9ac013a0b", "7c1699dfe0cf8ff607dbdcc1e9b9af1755371f92a68f706051cc8c37d447c905", "88e5fcfb52ee7b911e8bb6d6aa2fd21fbecc674eadd44118a9cc3863f938e735", "8defac2f2ccd6805ebf65f5eeb132adcf2ab57aa11fdf4c0dd5169a004710e7d", "98c7086708b163d425c67c7a91bad6e466bb99d797aa64f965e9d25c12111a5e", "9add70b36c5666a2ed02b43b335fe19002ee5235efd4b8a89bfcf9005bebac0d", "9bf40443012702a1d2070043cb6291650a0841ece432556f784f004937f0f32c", "ade5e387d2ad0d7ebf59146cc00c8044acbd863725f887353a10df825fc8ae21", "b00c1de48212e4cc9603895652c5c410df699856a2853135b3967591e4beebc2", "b1282f8c00509d99fef04d8ba936b156d419be841854fe901d8ae224c59f0be5", "b2051432115498d3562c084a49bba65d97cf251f5a331c64a12ee7e04dacc51b", "ba59edeaa2fc6114428f1637ffff42da1e311e29382d81b339c1817d37ec93c6", "c8716a48d94b06bb3b2524c2b77e055fb313aeb4ea620c8dd03a105574ba704f", "cd5df75523866410809ca100dc9681e301e3c27567cf498077e8551b6d20e42f", "e249096428b3ae81b08327a63a485ad0878de3fb939049038579ac0ef61e17e7"]
@@ -1076,8 +1096,8 @@ py = ["64f65755aee5b381cea27766a3a147c3f15b9b6b9ac88676de66ba2ae36793fa", "dc639
 pydocstyle = ["2258f9b0df68b97bf3a6c29003edc5238ff8879f1efb6f1999988d934e432bd8", "5741c85e408f9e0ddf873611085e819b809fca90b619f5fd7f34bd4959da3dd4", "ed79d4ec5e92655eccc21eb0c6cf512e69512b4a97d215ace46d17e4990f2039"]
 pygments = ["31cba6ffb739f099a85e243eff8cb717089fdd3c7300767d9fc34cb8e1b065f5", "5ad302949b3c98dd73f8d9fcdc7e9cb592f120e32a18e23efd7f3dc51194472b"]
 pylint = ["5d77031694a5fb97ea95e828c8d10fc770a1df6eb3906067aaed42201a8a6a09", "723e3db49555abaf9bf79dc474c6b9e2935ad82230b10c1138a71ea41ac0fff1"]
-pyrsistent = ["5403d37f4d55ff4572b5b5676890589f367a9569529c6f728c11046c4ea4272b"]
-pytest = ["136632a40451162cdfc18fe4d7ecc5d169b558a3d4bbb1603d4005308a42fd03", "62b129bf8368554ca7a942cbdb57ea26aafef46cc65bc317cdac3967e54483a3"]
+pyrsistent = ["16692ee739d42cf5e39cef8d27649a8c1fdb7aa99887098f1460057c5eb75c3a"]
+pytest = ["1a8aa4fa958f8f451ac5441f3ac130d9fc86ea38780dd2715e6d5c5882700b24", "b8bf138592384bd4e87338cb0f256bf5f615398a649d4bd83915f0e4047a5ca6"]
 pytest-cov = ["2b097cde81a302e1047331b48cadacf23577e431b61e9c6f49a1170bbe3d3da6", "e00ea4fdde970725482f1f35630d12f074e121a23801aabf2ae154ec6bdd343a"]
 pytest-describe = ["569bda96401fe512f4f345f33fd23fa4d718639d42afac62bc03254b5f2b3fdf"]
 pytest-expecter = ["1c8e9ab98ddd576436b61a7ba61ea11cfa5a3fc6b00288ce9e91e9dd770daf19", "27c93dfe87e2f4d28c525031be68d3f89457e3315241d97ee15f7689544e0e37"]
@@ -1103,6 +1123,8 @@ tomlkit = ["d6506342615d051bc961f70bfcfa3d29b6616cc08a3ddfd4bc24196f16fd4ec2", "
 tornado = ["1174dcb84d08887b55defb2cda1986faeeea715fff189ef3dc44cce99f5fca6b", "2613fab506bd2aedb3722c8c64c17f8f74f4070afed6eea17f20b2115e445aec", "44b82bc1146a24e5b9853d04c142576b4e8fa7a92f2e30bc364a85d1f75c4de2", "457fcbee4df737d2defc181b9073758d73f54a6cfc1f280533ff48831b39f4a8", "49603e1a6e24104961497ad0c07c799aec1caac7400a6762b687e74c8206677d", "8c2f40b99a8153893793559919a355d7b74649a11e59f411b0b0a1793e160bc0", "e1d897889c3b5a829426b7d52828fb37b28bc181cd598624e65c8be40ee3f7fa"]
 traitlets = ["9c4bd2d267b7153df9152698efb1050a5d84982d3384a37b2c1f7723ba3e7835", "c6cb5e6f57c5a9bdaa40fa71ce7b4af30298fbab9ece9815b5d995ab6217c7d9"]
 typed-ast = ["132eae51d6ef3ff4a8c47c393a4ef5ebf0d1aecc96880eb5d6c8ceab7017cc9b", "18141c1484ab8784006c839be8b985cfc82a2e9725837b0ecfa0203f71c4e39d", "2baf617f5bbbfe73fd8846463f5aeafc912b5ee247f410700245d68525ec584a", "3d90063f2cbbe39177e9b4d888e45777012652d6110156845b828908c51ae462", "4304b2218b842d610aa1a1d87e1dc9559597969acc62ce717ee4dfeaa44d7eee", "4983ede548ffc3541bae49a82675996497348e55bafd1554dc4e4a5d6eda541a", "5315f4509c1476718a4825f45a203b82d7fdf2a6f5f0c8f166435975b1c9f7d4", "6cdfb1b49d5345f7c2b90d638822d16ba62dc82f7616e9b4caa10b72f3f16649", "7b325f12635598c604690efd7a0197d0b94b7d7778498e76e0710cd582fd1c7a", "8d3b0e3b8626615826f9a626548057c5275a9733512b137984a68ba1598d3d2f", "8f8631160c79f53081bd23446525db0bc4c5616f78d04021e6e434b286493fd7", "912de10965f3dc89da23936f1cc4ed60764f712e5fa603a09dd904f88c996760", "b010c07b975fe853c65d7bbe9d4ac62f1c69086750a574f6292597763781ba18", "c908c10505904c48081a5415a1e295d8403e353e0c14c42b6d67f8f97fae6616", "c94dd3807c0c0610f7c76f078119f4ea48235a953512752b9175f9f98f5ae2bd", "ce65dee7594a84c466e79d7fb7d3303e7295d16a83c22c7c4037071b059e2c21", "eaa9cfcb221a8a4c2889be6f93da141ac777eb8819f077e1d09fb12d00a09a93", "f3376bc31bad66d46d44b4e6522c5c21976bf9bca4ef5987bb2bf727f4506cbb", "f9202fa138544e13a4ec1a6792c35834250a85958fde1251b6a22e07d1260ae7"]
+typing = ["4027c5f6127a6267a435201981ba156de91ad0d1d98e9ddc2aa173453453492d", "57dcf675a99b74d64dacf6fba08fb17cf7e3d5fdff53d4a30ea2a5e7e52543d4", "a4c8473ce11a65999c8f59cb093e70686b6c84c98df58c1dae9b3b196089858a"]
+typing-extensions = ["07b2c978670896022a43c4b915df8958bec4a6b84add7f2c87b2b728bda3ba64", "f3f0e67e1d42de47b5c67c32c9b26641642e9170fe7e292991793705cd5fef7c", "fb2cd053238d33a8ec939190f30cfd736c00653a85a2919415cecf7dc3d9da71"]
 urllib3 = ["2393a695cd12afedd0dcb26fe5d50d0cf248e5a66f75dbd89a3d4eb333a61af4", "a637e5fae88995b256e3409dc4d52c2e2e0ba32c42a6365fee8bbd2238de3cfb"]
 watchdog = ["965f658d0732de3188211932aeb0bb457587f04f63ab4c1e33eab878e9de961d"]
 wcwidth = ["3df37372226d6e63e1b1e1eda15c594bca98a22d33a23832a90998faa96bc65e", "f4ebe71925af7b40a864553f761ed559b43544f8f71746c2d756c7fe788ade7c"]
diff --git a/pyproject.toml b/pyproject.toml
index 6d538501..b18b4738 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -49,6 +49,9 @@ minilog = "^1.2.3"
 classproperties = "~0.1.3"
 cached_property = "^1.5"
 
+# Typing
+typing-extensions = "^3.7"
+
 [tool.poetry.dev-dependencies]
 
 # Formatters