diff --git a/Makefile b/Makefile
index c46332a3..08a4abec 100644
--- a/Makefile
+++ b/Makefile
@@ -29,12 +29,12 @@ test-system-browser-watch:
 
 build:
 	@rm -rf lib
-	@${BIN}/tsc
+	@${BIN}/tsc --project tsconfig.lib.json
 	@${BIN}/prettier "lib/**/*.[jt]s" --write --loglevel silent
 	@cp package.json lib
 	@cp *.md lib
 	@rsync --archive --prune-empty-dirs --exclude '*.ts' --relative src/./ lib
-	@${BIN}/tsc --outDir lib/esm --module es2020 --target es2019
+	@${BIN}/tsc --project tsconfig.lib.json --outDir lib/esm --module es2020 --target es2019
 	@cp src/adaptor/package.esm.json lib/esm/adaptor/package.json
 
 publish: build
diff --git a/package.json b/package.json
index 5f7738b6..09c678b7 100644
--- a/package.json
+++ b/package.json
@@ -1,6 +1,6 @@
 {
   "name": "typesaurus",
-  "version": "7.2.0",
+  "version": "8.0.0-alpha.1",
   "description": "Type-safe ODM for Firestore",
   "keywords": [
     "Firebase",
diff --git a/src/field/index.ts b/src/field/index.ts
index 9e250e5b..b988da05 100644
--- a/src/field/index.ts
+++ b/src/field/index.ts
@@ -1,5 +1,21 @@
 import { UpdateValue } from '../value'
 
+type Whole<Type, Key extends keyof Type> = Type[Key] extends
+  | infer Value
+  | undefined
+  ? Value
+  : never
+
+type PartialValue<
+  Model,
+  Key1 extends keyof Model,
+  Key2 extends keyof Whole<Model, Key1>
+> = Partial<Pick<Model, Key1>> extends Pick<Model, Key1>
+  ? Partial<Model[Key1]> extends Model[Key1]
+    ? Whole<Model, Key1>[Key2]
+    : never
+  : Whole<Model, Key1>[Key2]
+
 /**
  * The field type. It contains path to the property and property value.
  */
@@ -13,9 +29,13 @@ function field<Model, Key extends keyof Model>(
   value: Model[Key] | UpdateValue<Model, Key>
 ): Field<Model>
 
-function field<Model, Key1 extends keyof Model, Key2 extends keyof Model[Key1]>(
+function field<
+  Model,
+  Key1 extends keyof Model,
+  Key2 extends keyof Whole<Model, Key1>
+>(
   key: [Key1, Key2],
-  value: Model[Key1][Key2] | UpdateValue<Model[Key1], Key2>
+  value: PartialValue<Model, Key1, Key2> | UpdateValue<Whole<Model, Key1>, Key2>
 ): Field<Model>
 
 function field<
diff --git a/src/field/test.ts b/src/field/test.ts
index dfb75ab0..027d80f2 100644
--- a/src/field/test.ts
+++ b/src/field/test.ts
@@ -17,14 +17,44 @@ describe('field', () => {
   })
 
   it('disallows deleting required fields', () => {
-    type TestModel = { a: { b: { c: number; d?: string } }; e?: string }
+    type TestModel = {
+      a: { b: { c: number; d?: string } }
+      e?: string
+      f?: { [key: string]: number | undefined }
+    }
     // @ts-expect-error
     assertField<TestModel>(field(['a', 'b', 'c'], value('remove')))
     assertField<TestModel>(field(['a', 'b', 'c'], value('increment', 1)))
     assertField<TestModel>(field(['a', 'b', 'd'], value('remove')))
     assertField<TestModel>(field('e', 'ok'))
     assertField<TestModel>(field('e', value('remove')))
+    assertField<TestModel>(field(['f', 'ok'], value('remove')))
+  })
+
+  it('allows updating fields in optional partial objects', () => {
+    type TestModel = {
+      a?: { b?: number; c?: string }
+      d?: { e: number; f: string }
+      g?: { [key: string]: number | undefined }
+      h?: { [key: string]: number }
+      i: { j: number; k: string }
+      l?: { [key: string]: string | undefined }
+    }
+    assertField<TestModel>(field(['a', 'b'], 123))
+    assertField<TestModel>(field(['a', 'b'], value('remove')))
+    // @ts-expect-error
+    assertField<TestModel>(field(['d', 'e'], 123))
+    // @ts-expect-error
+    assertField<TestModel>(field(['d', 'e'], value('remove')))
+    assertField<TestModel>(field(['g', 'qwe'], 123))
+    assertField<TestModel>(field(['i', 'j'], 123))
+    assertField<TestModel>(field(['g', 'ok'], value('increment', 1)))
+    assertField<TestModel>(field(['h', 'ok'], value('increment', 1)))
+    // @ts-expect-error
+    assertField<TestModel>(field(['h', 'nope'], 123))
+    // @ts-expect-error
+    assertField<TestModel>(field(['k', 'nope'], value('increment', 1)))
   })
 })
 
-function assertField<Model>(fields: Field<Model>) {}
+function assertField<Model>(_field: Field<Model>) {}
diff --git a/src/value/index.ts b/src/value/index.ts
index 2b7b1e5d..b71d6066 100644
--- a/src/value/index.ts
+++ b/src/value/index.ts
@@ -60,22 +60,27 @@ type MaybeValueRemoveOr<Model, Key extends keyof Model, ValueType> = Partial<
 type MaybeValueRemove<Model, Key extends keyof Model> = Partial<
   Pick<Model, Key>
 > extends Pick<Model, Key>
+  ? ValueRemove
+  : Undefined<Model[Key]> extends Model[Key]
   ? ValueRemove
   : never
 
+type Undefined<T> = T extends undefined ? T : never
+
 /**
  * The value types to use for update operation.
  */
-export type UpdateValue<
-  Model,
-  Key extends keyof Model
-> = Model[Key] extends number
-  ? MaybeValueRemoveOr<Model, Key, ValueIncrement>
-  : Model[Key] extends Array<any>
-  ? MaybeValueRemoveOr<Model, Key, ValueArrayUnion | ValueArrayRemove>
-  : Model[Key] extends Date
-  ? MaybeValueRemoveOr<Model, Key, ValueServerDate>
-  : MaybeValueRemove<Model, Key>
+export type UpdateValue<Model, Key> = Key extends keyof Model
+  ? Model[Key] extends infer Type
+    ? Type extends number
+      ? MaybeValueRemoveOr<Model, Key, ValueIncrement>
+      : Type extends Array<any>
+      ? MaybeValueRemoveOr<Model, Key, ValueArrayUnion | ValueArrayRemove>
+      : Type extends Date
+      ? MaybeValueRemoveOr<Model, Key, ValueServerDate>
+      : MaybeValueRemove<Model, Key>
+    : never
+  : never
 
 /**
  * The value types to use for add operation.
diff --git a/tsconfig.json b/tsconfig.json
index e67aed61..d15268bd 100644
--- a/tsconfig.json
+++ b/tsconfig.json
@@ -8,9 +8,8 @@
     "sourceMap": true,
     "outDir": "lib",
     "strict": true,
-    "noImplicitAny": true,
     "esModuleInterop": true,
     "resolveJsonModule": true
   },
-  "exclude": ["**/test.ts", "lib", "node_modules", "test"]
+  "exclude": ["lib", "node_modules"]
 }
diff --git a/tsconfig.lib.json b/tsconfig.lib.json
new file mode 100644
index 00000000..99882b4f
--- /dev/null
+++ b/tsconfig.lib.json
@@ -0,0 +1,4 @@
+{
+  "extends": "./tsconfig",
+  "exclude": ["lib", "node_modules", "**/test.ts", "test"]
+}