diff --git a/src/compiler/checker.ts b/src/compiler/checker.ts
index caab75c99fa8a..5c1f4593aa251 100644
--- a/src/compiler/checker.ts
+++ b/src/compiler/checker.ts
@@ -30452,7 +30452,7 @@ export function createTypeChecker(host: TypeCheckerHost): TypeChecker {
// We only look for uninitialized variables in strict null checking mode, and only when we can analyze
// the entire control flow graph from the variable's declaration (i.e. when the flow container and
// declaration container are the same).
- const isNeverInitialized = immediateDeclaration && isVariableDeclaration(immediateDeclaration) && !immediateDeclaration.initializer && !immediateDeclaration.exclamationToken && isMutableLocalVariableDeclaration(immediateDeclaration) && !isSymbolAssignedDefinitely(symbol);
+ const isNeverInitialized = immediateDeclaration && isVariableDeclaration(immediateDeclaration) && !isForInOrOfStatement(immediateDeclaration.parent.parent) && !immediateDeclaration.initializer && !immediateDeclaration.exclamationToken && isMutableLocalVariableDeclaration(immediateDeclaration) && !isSymbolAssignedDefinitely(symbol);
const assumeInitialized = isParameter || isAlias ||
(isOuterVariable && !isNeverInitialized) ||
isSpreadDestructuringAssignmentTarget || isModuleExports || isSameScopedBindingElement(node, declaration) ||
diff --git a/tests/baselines/reference/unusedLocalsInForInOrOf1.errors.txt b/tests/baselines/reference/unusedLocalsInForInOrOf1.errors.txt
new file mode 100644
index 0000000000000..2b0a014ec961b
--- /dev/null
+++ b/tests/baselines/reference/unusedLocalsInForInOrOf1.errors.txt
@@ -0,0 +1,84 @@
+unusedLocalsInForInOrOf1.ts(2,12): error TS6133: 'f' is declared but its value is never read.
+unusedLocalsInForInOrOf1.ts(8,7): error TS6133: 'f' is declared but its value is never read.
+unusedLocalsInForInOrOf1.ts(14,12): error TS6133: 'g' is declared but its value is never read.
+unusedLocalsInForInOrOf1.ts(20,12): error TS6133: 'f2' is declared but its value is never read.
+unusedLocalsInForInOrOf1.ts(26,7): error TS6133: 'f2' is declared but its value is never read.
+unusedLocalsInForInOrOf1.ts(32,12): error TS6133: 'g2' is declared but its value is never read.
+unusedLocalsInForInOrOf1.ts(38,12): error TS6133: 'f3' is declared but its value is never read.
+unusedLocalsInForInOrOf1.ts(44,7): error TS6133: 'f3' is declared but its value is never read.
+unusedLocalsInForInOrOf1.ts(50,12): error TS6133: 'g3' is declared but its value is never read.
+
+
+==== unusedLocalsInForInOrOf1.ts (9 errors) ====
+ for (let x of [1, 2]) {
+ function f() {
+ ~
+!!! error TS6133: 'f' is declared but its value is never read.
+ x;
+ }
+ }
+
+ for (let x of [1, 2]) {
+ let f = () => {
+ ~
+!!! error TS6133: 'f' is declared but its value is never read.
+ x;
+ };
+ }
+
+ for (const x of [1, 2]) {
+ function g() {
+ ~
+!!! error TS6133: 'g' is declared but its value is never read.
+ x;
+ }
+ }
+
+ for (let x in { a: 1, b: 2 }) {
+ function f2() {
+ ~~
+!!! error TS6133: 'f2' is declared but its value is never read.
+ x;
+ }
+ }
+
+ for (let x in { a: 1, b: 2 }) {
+ let f2 = () => {
+ ~~
+!!! error TS6133: 'f2' is declared but its value is never read.
+ x;
+ };
+ }
+
+ for (const x in { a: 1, b: 2 }) {
+ function g2() {
+ ~~
+!!! error TS6133: 'g2' is declared but its value is never read.
+ x;
+ }
+ }
+
+ for (let { x } of [{ x: 1 }, { x: 2 }]) {
+ function f3() {
+ ~~
+!!! error TS6133: 'f3' is declared but its value is never read.
+ x;
+ }
+ }
+
+ for (let { x } of [{ x: 1 }, { x: 2 }]) {
+ let f3 = () => {
+ ~~
+!!! error TS6133: 'f3' is declared but its value is never read.
+ x;
+ };
+ }
+
+ for (const { x } of [{ x: 1 }, { x: 2 }]) {
+ function g3() {
+ ~~
+!!! error TS6133: 'g3' is declared but its value is never read.
+ x;
+ }
+ }
+
\ No newline at end of file
diff --git a/tests/baselines/reference/unusedLocalsInForInOrOf1.symbols b/tests/baselines/reference/unusedLocalsInForInOrOf1.symbols
new file mode 100644
index 0000000000000..c4c2381baff5d
--- /dev/null
+++ b/tests/baselines/reference/unusedLocalsInForInOrOf1.symbols
@@ -0,0 +1,117 @@
+//// [tests/cases/compiler/unusedLocalsInForInOrOf1.ts] ////
+
+=== unusedLocalsInForInOrOf1.ts ===
+for (let x of [1, 2]) {
+>x : Symbol(x, Decl(unusedLocalsInForInOrOf1.ts, 0, 8))
+
+ function f() {
+>f : Symbol(f, Decl(unusedLocalsInForInOrOf1.ts, 0, 23))
+
+ x;
+>x : Symbol(x, Decl(unusedLocalsInForInOrOf1.ts, 0, 8))
+ }
+}
+
+for (let x of [1, 2]) {
+>x : Symbol(x, Decl(unusedLocalsInForInOrOf1.ts, 6, 8))
+
+ let f = () => {
+>f : Symbol(f, Decl(unusedLocalsInForInOrOf1.ts, 7, 5))
+
+ x;
+>x : Symbol(x, Decl(unusedLocalsInForInOrOf1.ts, 6, 8))
+
+ };
+}
+
+for (const x of [1, 2]) {
+>x : Symbol(x, Decl(unusedLocalsInForInOrOf1.ts, 12, 10))
+
+ function g() {
+>g : Symbol(g, Decl(unusedLocalsInForInOrOf1.ts, 12, 25))
+
+ x;
+>x : Symbol(x, Decl(unusedLocalsInForInOrOf1.ts, 12, 10))
+ }
+}
+
+for (let x in { a: 1, b: 2 }) {
+>x : Symbol(x, Decl(unusedLocalsInForInOrOf1.ts, 18, 8))
+>a : Symbol(a, Decl(unusedLocalsInForInOrOf1.ts, 18, 15))
+>b : Symbol(b, Decl(unusedLocalsInForInOrOf1.ts, 18, 21))
+
+ function f2() {
+>f2 : Symbol(f2, Decl(unusedLocalsInForInOrOf1.ts, 18, 31))
+
+ x;
+>x : Symbol(x, Decl(unusedLocalsInForInOrOf1.ts, 18, 8))
+ }
+}
+
+for (let x in { a: 1, b: 2 }) {
+>x : Symbol(x, Decl(unusedLocalsInForInOrOf1.ts, 24, 8))
+>a : Symbol(a, Decl(unusedLocalsInForInOrOf1.ts, 24, 15))
+>b : Symbol(b, Decl(unusedLocalsInForInOrOf1.ts, 24, 21))
+
+ let f2 = () => {
+>f2 : Symbol(f2, Decl(unusedLocalsInForInOrOf1.ts, 25, 5))
+
+ x;
+>x : Symbol(x, Decl(unusedLocalsInForInOrOf1.ts, 24, 8))
+
+ };
+}
+
+for (const x in { a: 1, b: 2 }) {
+>x : Symbol(x, Decl(unusedLocalsInForInOrOf1.ts, 30, 10))
+>a : Symbol(a, Decl(unusedLocalsInForInOrOf1.ts, 30, 17))
+>b : Symbol(b, Decl(unusedLocalsInForInOrOf1.ts, 30, 23))
+
+ function g2() {
+>g2 : Symbol(g2, Decl(unusedLocalsInForInOrOf1.ts, 30, 33))
+
+ x;
+>x : Symbol(x, Decl(unusedLocalsInForInOrOf1.ts, 30, 10))
+ }
+}
+
+for (let { x } of [{ x: 1 }, { x: 2 }]) {
+>x : Symbol(x, Decl(unusedLocalsInForInOrOf1.ts, 36, 10))
+>x : Symbol(x, Decl(unusedLocalsInForInOrOf1.ts, 36, 20))
+>x : Symbol(x, Decl(unusedLocalsInForInOrOf1.ts, 36, 30))
+
+ function f3() {
+>f3 : Symbol(f3, Decl(unusedLocalsInForInOrOf1.ts, 36, 41))
+
+ x;
+>x : Symbol(x, Decl(unusedLocalsInForInOrOf1.ts, 36, 10))
+ }
+}
+
+for (let { x } of [{ x: 1 }, { x: 2 }]) {
+>x : Symbol(x, Decl(unusedLocalsInForInOrOf1.ts, 42, 10))
+>x : Symbol(x, Decl(unusedLocalsInForInOrOf1.ts, 42, 20))
+>x : Symbol(x, Decl(unusedLocalsInForInOrOf1.ts, 42, 30))
+
+ let f3 = () => {
+>f3 : Symbol(f3, Decl(unusedLocalsInForInOrOf1.ts, 43, 5))
+
+ x;
+>x : Symbol(x, Decl(unusedLocalsInForInOrOf1.ts, 42, 10))
+
+ };
+}
+
+for (const { x } of [{ x: 1 }, { x: 2 }]) {
+>x : Symbol(x, Decl(unusedLocalsInForInOrOf1.ts, 48, 12))
+>x : Symbol(x, Decl(unusedLocalsInForInOrOf1.ts, 48, 22))
+>x : Symbol(x, Decl(unusedLocalsInForInOrOf1.ts, 48, 32))
+
+ function g3() {
+>g3 : Symbol(g3, Decl(unusedLocalsInForInOrOf1.ts, 48, 43))
+
+ x;
+>x : Symbol(x, Decl(unusedLocalsInForInOrOf1.ts, 48, 12))
+ }
+}
+
diff --git a/tests/baselines/reference/unusedLocalsInForInOrOf1.types b/tests/baselines/reference/unusedLocalsInForInOrOf1.types
new file mode 100644
index 0000000000000..cf2e52be73799
--- /dev/null
+++ b/tests/baselines/reference/unusedLocalsInForInOrOf1.types
@@ -0,0 +1,228 @@
+//// [tests/cases/compiler/unusedLocalsInForInOrOf1.ts] ////
+
+=== unusedLocalsInForInOrOf1.ts ===
+for (let x of [1, 2]) {
+>x : number
+> : ^^^^^^
+>[1, 2] : number[]
+> : ^^^^^^^^
+>1 : 1
+> : ^
+>2 : 2
+> : ^
+
+ function f() {
+>f : () => void
+> : ^^^^^^^^^^
+
+ x;
+>x : number
+> : ^^^^^^
+ }
+}
+
+for (let x of [1, 2]) {
+>x : number
+> : ^^^^^^
+>[1, 2] : number[]
+> : ^^^^^^^^
+>1 : 1
+> : ^
+>2 : 2
+> : ^
+
+ let f = () => {
+>f : () => void
+> : ^^^^^^^^^^
+>() => { x; } : () => void
+> : ^^^^^^^^^^
+
+ x;
+>x : number
+> : ^^^^^^
+
+ };
+}
+
+for (const x of [1, 2]) {
+>x : number
+> : ^^^^^^
+>[1, 2] : number[]
+> : ^^^^^^^^
+>1 : 1
+> : ^
+>2 : 2
+> : ^
+
+ function g() {
+>g : () => void
+> : ^^^^^^^^^^
+
+ x;
+>x : number
+> : ^^^^^^
+ }
+}
+
+for (let x in { a: 1, b: 2 }) {
+>x : string
+> : ^^^^^^
+>{ a: 1, b: 2 } : { a: number; b: number; }
+> : ^^^^^^^^^^^^^^^^^^^^^^^^^
+>a : number
+> : ^^^^^^
+>1 : 1
+> : ^
+>b : number
+> : ^^^^^^
+>2 : 2
+> : ^
+
+ function f2() {
+>f2 : () => void
+> : ^^^^^^^^^^
+
+ x;
+>x : string
+> : ^^^^^^
+ }
+}
+
+for (let x in { a: 1, b: 2 }) {
+>x : string
+> : ^^^^^^
+>{ a: 1, b: 2 } : { a: number; b: number; }
+> : ^^^^^^^^^^^^^^^^^^^^^^^^^
+>a : number
+> : ^^^^^^
+>1 : 1
+> : ^
+>b : number
+> : ^^^^^^
+>2 : 2
+> : ^
+
+ let f2 = () => {
+>f2 : () => void
+> : ^^^^^^^^^^
+>() => { x; } : () => void
+> : ^^^^^^^^^^
+
+ x;
+>x : string
+> : ^^^^^^
+
+ };
+}
+
+for (const x in { a: 1, b: 2 }) {
+>x : string
+> : ^^^^^^
+>{ a: 1, b: 2 } : { a: number; b: number; }
+> : ^^^^^^^^^^^^^^^^^^^^^^^^^
+>a : number
+> : ^^^^^^
+>1 : 1
+> : ^
+>b : number
+> : ^^^^^^
+>2 : 2
+> : ^
+
+ function g2() {
+>g2 : () => void
+> : ^^^^^^^^^^
+
+ x;
+>x : string
+> : ^^^^^^
+ }
+}
+
+for (let { x } of [{ x: 1 }, { x: 2 }]) {
+>x : number
+> : ^^^^^^
+>[{ x: 1 }, { x: 2 }] : { x: number; }[]
+> : ^^^^^^^^^^^^^^^^
+>{ x: 1 } : { x: number; }
+> : ^^^^^^^^^^^^^^
+>x : number
+> : ^^^^^^
+>1 : 1
+> : ^
+>{ x: 2 } : { x: number; }
+> : ^^^^^^^^^^^^^^
+>x : number
+> : ^^^^^^
+>2 : 2
+> : ^
+
+ function f3() {
+>f3 : () => void
+> : ^^^^^^^^^^
+
+ x;
+>x : number
+> : ^^^^^^
+ }
+}
+
+for (let { x } of [{ x: 1 }, { x: 2 }]) {
+>x : number
+> : ^^^^^^
+>[{ x: 1 }, { x: 2 }] : { x: number; }[]
+> : ^^^^^^^^^^^^^^^^
+>{ x: 1 } : { x: number; }
+> : ^^^^^^^^^^^^^^
+>x : number
+> : ^^^^^^
+>1 : 1
+> : ^
+>{ x: 2 } : { x: number; }
+> : ^^^^^^^^^^^^^^
+>x : number
+> : ^^^^^^
+>2 : 2
+> : ^
+
+ let f3 = () => {
+>f3 : () => void
+> : ^^^^^^^^^^
+>() => { x; } : () => void
+> : ^^^^^^^^^^
+
+ x;
+>x : number
+> : ^^^^^^
+
+ };
+}
+
+for (const { x } of [{ x: 1 }, { x: 2 }]) {
+>x : number
+> : ^^^^^^
+>[{ x: 1 }, { x: 2 }] : { x: number; }[]
+> : ^^^^^^^^^^^^^^^^
+>{ x: 1 } : { x: number; }
+> : ^^^^^^^^^^^^^^
+>x : number
+> : ^^^^^^
+>1 : 1
+> : ^
+>{ x: 2 } : { x: number; }
+> : ^^^^^^^^^^^^^^
+>x : number
+> : ^^^^^^
+>2 : 2
+> : ^
+
+ function g3() {
+>g3 : () => void
+> : ^^^^^^^^^^
+
+ x;
+>x : number
+> : ^^^^^^
+ }
+}
+
diff --git a/tests/cases/compiler/unusedLocalsInForInOrOf1.ts b/tests/cases/compiler/unusedLocalsInForInOrOf1.ts
new file mode 100644
index 0000000000000..edbdad5c59069
--- /dev/null
+++ b/tests/cases/compiler/unusedLocalsInForInOrOf1.ts
@@ -0,0 +1,59 @@
+// @strict: true
+// @target: esnext
+// @noEmit: true
+// @noUnusedLocals: true
+// @noUnusedParameters: true
+
+for (let x of [1, 2]) {
+ function f() {
+ x;
+ }
+}
+
+for (let x of [1, 2]) {
+ let f = () => {
+ x;
+ };
+}
+
+for (const x of [1, 2]) {
+ function g() {
+ x;
+ }
+}
+
+for (let x in { a: 1, b: 2 }) {
+ function f2() {
+ x;
+ }
+}
+
+for (let x in { a: 1, b: 2 }) {
+ let f2 = () => {
+ x;
+ };
+}
+
+for (const x in { a: 1, b: 2 }) {
+ function g2() {
+ x;
+ }
+}
+
+for (let { x } of [{ x: 1 }, { x: 2 }]) {
+ function f3() {
+ x;
+ }
+}
+
+for (let { x } of [{ x: 1 }, { x: 2 }]) {
+ let f3 = () => {
+ x;
+ };
+}
+
+for (const { x } of [{ x: 1 }, { x: 2 }]) {
+ function g3() {
+ x;
+ }
+}