diff --git a/src/compiler/checker.ts b/src/compiler/checker.ts
index da31a1c39c6..e4c2bf2250f 100644
--- a/src/compiler/checker.ts
+++ b/src/compiler/checker.ts
@@ -19709,7 +19709,8 @@ namespace ts {
         // arrow function, but is considered partially inferable because property 'a' has an inferable type.
         function isPartiallyInferableType(type: Type): boolean {
             return !(getObjectFlags(type) & ObjectFlags.NonInferrableType) ||
-                isObjectLiteralType(type) && some(getPropertiesOfType(type), prop => isPartiallyInferableType(getTypeOfSymbol(prop)));
+                isObjectLiteralType(type) && some(getPropertiesOfType(type), prop => isPartiallyInferableType(getTypeOfSymbol(prop))) ||
+                isTupleType(type) && some(getTypeArguments(type), isPartiallyInferableType);
         }
 
         function createReverseMappedType(source: Type, target: MappedType, constraint: IndexType) {
diff --git a/tests/baselines/reference/reverseMappedPartiallyInferableTypes.errors.txt b/tests/baselines/reference/reverseMappedPartiallyInferableTypes.errors.txt
index 63ea9a9f279..bd3697aaaff 100644
--- a/tests/baselines/reference/reverseMappedPartiallyInferableTypes.errors.txt
+++ b/tests/baselines/reference/reverseMappedPartiallyInferableTypes.errors.txt
@@ -98,4 +98,36 @@ tests/cases/compiler/reverseMappedPartiallyInferableTypes.ts(91,20): error TS257
             }
         }
     });
+    
+    // Repros from #40809
+    
+    type Mapped1<T> = {
+        [K in keyof T]: [T[K], (arg: T) => boolean];
+    };
+    
+    declare function inferMapped1<T>(arg: Mapped1<T>): void;
+    
+    inferMapped1({
+        key: [3, arg => arg.key > 5]
+    });
+    
+    type Mapped2<T> = {
+        [K in keyof T]: [T[K], unknown extends T ? unknown : (arg: T) => boolean];
+    };
+    
+    declare function inferMapped2<T>(arg: Mapped2<T>): void;
+    
+    inferMapped2({
+        key: [3, arg => arg.key > 5]
+    });
+    
+    type MappedReadonly<T> = {
+        readonly [K in keyof T]: readonly [T[K], (arg: T) => boolean];
+    };
+    
+    declare function inferMappedReadonly<T>(arg: MappedReadonly<T>): void;
+    
+    inferMappedReadonly({
+        key: [3, arg => arg.key > 5]
+    });
     
\ No newline at end of file
diff --git a/tests/baselines/reference/reverseMappedPartiallyInferableTypes.js b/tests/baselines/reference/reverseMappedPartiallyInferableTypes.js
index e5a9c2a57ae..fbd70a5bb65 100644
--- a/tests/baselines/reference/reverseMappedPartiallyInferableTypes.js
+++ b/tests/baselines/reference/reverseMappedPartiallyInferableTypes.js
@@ -93,6 +93,38 @@ const obj3 = id({
         }
     }
 });
+
+// Repros from #40809
+
+type Mapped1<T> = {
+    [K in keyof T]: [T[K], (arg: T) => boolean];
+};
+
+declare function inferMapped1<T>(arg: Mapped1<T>): void;
+
+inferMapped1({
+    key: [3, arg => arg.key > 5]
+});
+
+type Mapped2<T> = {
+    [K in keyof T]: [T[K], unknown extends T ? unknown : (arg: T) => boolean];
+};
+
+declare function inferMapped2<T>(arg: Mapped2<T>): void;
+
+inferMapped2({
+    key: [3, arg => arg.key > 5]
+});
+
+type MappedReadonly<T> = {
+    readonly [K in keyof T]: readonly [T[K], (arg: T) => boolean];
+};
+
+declare function inferMappedReadonly<T>(arg: MappedReadonly<T>): void;
+
+inferMappedReadonly({
+    key: [3, arg => arg.key > 5]
+});
 
 
 //// [reverseMappedPartiallyInferableTypes.js]
@@ -142,3 +174,12 @@ var obj3 = id({
         }
     }
 });
+inferMapped1({
+    key: [3, function (arg) { return arg.key > 5; }]
+});
+inferMapped2({
+    key: [3, function (arg) { return arg.key > 5; }]
+});
+inferMappedReadonly({
+    key: [3, function (arg) { return arg.key > 5; }]
+});
diff --git a/tests/baselines/reference/reverseMappedPartiallyInferableTypes.symbols b/tests/baselines/reference/reverseMappedPartiallyInferableTypes.symbols
index ac264a37e9e..6ababcbb9f1 100644
--- a/tests/baselines/reference/reverseMappedPartiallyInferableTypes.symbols
+++ b/tests/baselines/reference/reverseMappedPartiallyInferableTypes.symbols
@@ -257,3 +257,105 @@ const obj3 = id({
     }
 });
 
+// Repros from #40809
+
+type Mapped1<T> = {
+>Mapped1 : Symbol(Mapped1, Decl(reverseMappedPartiallyInferableTypes.ts, 93, 3))
+>T : Symbol(T, Decl(reverseMappedPartiallyInferableTypes.ts, 97, 13))
+
+    [K in keyof T]: [T[K], (arg: T) => boolean];
+>K : Symbol(K, Decl(reverseMappedPartiallyInferableTypes.ts, 98, 5))
+>T : Symbol(T, Decl(reverseMappedPartiallyInferableTypes.ts, 97, 13))
+>T : Symbol(T, Decl(reverseMappedPartiallyInferableTypes.ts, 97, 13))
+>K : Symbol(K, Decl(reverseMappedPartiallyInferableTypes.ts, 98, 5))
+>arg : Symbol(arg, Decl(reverseMappedPartiallyInferableTypes.ts, 98, 28))
+>T : Symbol(T, Decl(reverseMappedPartiallyInferableTypes.ts, 97, 13))
+
+};
+
+declare function inferMapped1<T>(arg: Mapped1<T>): void;
+>inferMapped1 : Symbol(inferMapped1, Decl(reverseMappedPartiallyInferableTypes.ts, 99, 2))
+>T : Symbol(T, Decl(reverseMappedPartiallyInferableTypes.ts, 101, 30))
+>arg : Symbol(arg, Decl(reverseMappedPartiallyInferableTypes.ts, 101, 33))
+>Mapped1 : Symbol(Mapped1, Decl(reverseMappedPartiallyInferableTypes.ts, 93, 3))
+>T : Symbol(T, Decl(reverseMappedPartiallyInferableTypes.ts, 101, 30))
+
+inferMapped1({
+>inferMapped1 : Symbol(inferMapped1, Decl(reverseMappedPartiallyInferableTypes.ts, 99, 2))
+
+    key: [3, arg => arg.key > 5]
+>key : Symbol(key, Decl(reverseMappedPartiallyInferableTypes.ts, 103, 14))
+>arg : Symbol(arg, Decl(reverseMappedPartiallyInferableTypes.ts, 104, 12))
+>arg.key : Symbol(key, Decl(reverseMappedPartiallyInferableTypes.ts, 103, 14))
+>arg : Symbol(arg, Decl(reverseMappedPartiallyInferableTypes.ts, 104, 12))
+>key : Symbol(key, Decl(reverseMappedPartiallyInferableTypes.ts, 103, 14))
+
+});
+
+type Mapped2<T> = {
+>Mapped2 : Symbol(Mapped2, Decl(reverseMappedPartiallyInferableTypes.ts, 105, 3))
+>T : Symbol(T, Decl(reverseMappedPartiallyInferableTypes.ts, 107, 13))
+
+    [K in keyof T]: [T[K], unknown extends T ? unknown : (arg: T) => boolean];
+>K : Symbol(K, Decl(reverseMappedPartiallyInferableTypes.ts, 108, 5))
+>T : Symbol(T, Decl(reverseMappedPartiallyInferableTypes.ts, 107, 13))
+>T : Symbol(T, Decl(reverseMappedPartiallyInferableTypes.ts, 107, 13))
+>K : Symbol(K, Decl(reverseMappedPartiallyInferableTypes.ts, 108, 5))
+>T : Symbol(T, Decl(reverseMappedPartiallyInferableTypes.ts, 107, 13))
+>arg : Symbol(arg, Decl(reverseMappedPartiallyInferableTypes.ts, 108, 58))
+>T : Symbol(T, Decl(reverseMappedPartiallyInferableTypes.ts, 107, 13))
+
+};
+
+declare function inferMapped2<T>(arg: Mapped2<T>): void;
+>inferMapped2 : Symbol(inferMapped2, Decl(reverseMappedPartiallyInferableTypes.ts, 109, 2))
+>T : Symbol(T, Decl(reverseMappedPartiallyInferableTypes.ts, 111, 30))
+>arg : Symbol(arg, Decl(reverseMappedPartiallyInferableTypes.ts, 111, 33))
+>Mapped2 : Symbol(Mapped2, Decl(reverseMappedPartiallyInferableTypes.ts, 105, 3))
+>T : Symbol(T, Decl(reverseMappedPartiallyInferableTypes.ts, 111, 30))
+
+inferMapped2({
+>inferMapped2 : Symbol(inferMapped2, Decl(reverseMappedPartiallyInferableTypes.ts, 109, 2))
+
+    key: [3, arg => arg.key > 5]
+>key : Symbol(key, Decl(reverseMappedPartiallyInferableTypes.ts, 113, 14))
+>arg : Symbol(arg, Decl(reverseMappedPartiallyInferableTypes.ts, 114, 12))
+>arg.key : Symbol(key, Decl(reverseMappedPartiallyInferableTypes.ts, 113, 14))
+>arg : Symbol(arg, Decl(reverseMappedPartiallyInferableTypes.ts, 114, 12))
+>key : Symbol(key, Decl(reverseMappedPartiallyInferableTypes.ts, 113, 14))
+
+});
+
+type MappedReadonly<T> = {
+>MappedReadonly : Symbol(MappedReadonly, Decl(reverseMappedPartiallyInferableTypes.ts, 115, 3))
+>T : Symbol(T, Decl(reverseMappedPartiallyInferableTypes.ts, 117, 20))
+
+    readonly [K in keyof T]: readonly [T[K], (arg: T) => boolean];
+>K : Symbol(K, Decl(reverseMappedPartiallyInferableTypes.ts, 118, 14))
+>T : Symbol(T, Decl(reverseMappedPartiallyInferableTypes.ts, 117, 20))
+>T : Symbol(T, Decl(reverseMappedPartiallyInferableTypes.ts, 117, 20))
+>K : Symbol(K, Decl(reverseMappedPartiallyInferableTypes.ts, 118, 14))
+>arg : Symbol(arg, Decl(reverseMappedPartiallyInferableTypes.ts, 118, 46))
+>T : Symbol(T, Decl(reverseMappedPartiallyInferableTypes.ts, 117, 20))
+
+};
+
+declare function inferMappedReadonly<T>(arg: MappedReadonly<T>): void;
+>inferMappedReadonly : Symbol(inferMappedReadonly, Decl(reverseMappedPartiallyInferableTypes.ts, 119, 2))
+>T : Symbol(T, Decl(reverseMappedPartiallyInferableTypes.ts, 121, 37))
+>arg : Symbol(arg, Decl(reverseMappedPartiallyInferableTypes.ts, 121, 40))
+>MappedReadonly : Symbol(MappedReadonly, Decl(reverseMappedPartiallyInferableTypes.ts, 115, 3))
+>T : Symbol(T, Decl(reverseMappedPartiallyInferableTypes.ts, 121, 37))
+
+inferMappedReadonly({
+>inferMappedReadonly : Symbol(inferMappedReadonly, Decl(reverseMappedPartiallyInferableTypes.ts, 119, 2))
+
+    key: [3, arg => arg.key > 5]
+>key : Symbol(key, Decl(reverseMappedPartiallyInferableTypes.ts, 123, 21))
+>arg : Symbol(arg, Decl(reverseMappedPartiallyInferableTypes.ts, 124, 12))
+>arg.key : Symbol(key, Decl(reverseMappedPartiallyInferableTypes.ts, 123, 21))
+>arg : Symbol(arg, Decl(reverseMappedPartiallyInferableTypes.ts, 124, 12))
+>key : Symbol(key, Decl(reverseMappedPartiallyInferableTypes.ts, 123, 21))
+
+});
+
diff --git a/tests/baselines/reference/reverseMappedPartiallyInferableTypes.types b/tests/baselines/reference/reverseMappedPartiallyInferableTypes.types
index e2b8ba8b5fa..8a06b7c6d5e 100644
--- a/tests/baselines/reference/reverseMappedPartiallyInferableTypes.types
+++ b/tests/baselines/reference/reverseMappedPartiallyInferableTypes.types
@@ -229,3 +229,98 @@ const obj3 = id({
     }
 });
 
+// Repros from #40809
+
+type Mapped1<T> = {
+>Mapped1 : Mapped1<T>
+
+    [K in keyof T]: [T[K], (arg: T) => boolean];
+>arg : T
+
+};
+
+declare function inferMapped1<T>(arg: Mapped1<T>): void;
+>inferMapped1 : <T>(arg: Mapped1<T>) => void
+>arg : Mapped1<T>
+
+inferMapped1({
+>inferMapped1({    key: [3, arg => arg.key > 5]}) : void
+>inferMapped1 : <T>(arg: Mapped1<T>) => void
+>{    key: [3, arg => arg.key > 5]} : { key: [number, (arg: { key: number; }) => boolean]; }
+
+    key: [3, arg => arg.key > 5]
+>key : [number, (arg: { key: number; }) => boolean]
+>[3, arg => arg.key > 5] : [number, (arg: { key: number; }) => boolean]
+>3 : 3
+>arg => arg.key > 5 : (arg: { key: number; }) => boolean
+>arg : { key: number; }
+>arg.key > 5 : boolean
+>arg.key : number
+>arg : { key: number; }
+>key : number
+>5 : 5
+
+});
+
+type Mapped2<T> = {
+>Mapped2 : Mapped2<T>
+
+    [K in keyof T]: [T[K], unknown extends T ? unknown : (arg: T) => boolean];
+>arg : T
+
+};
+
+declare function inferMapped2<T>(arg: Mapped2<T>): void;
+>inferMapped2 : <T>(arg: Mapped2<T>) => void
+>arg : Mapped2<T>
+
+inferMapped2({
+>inferMapped2({    key: [3, arg => arg.key > 5]}) : void
+>inferMapped2 : <T>(arg: Mapped2<T>) => void
+>{    key: [3, arg => arg.key > 5]} : { key: [number, (arg: { key: number; }) => boolean]; }
+
+    key: [3, arg => arg.key > 5]
+>key : [number, (arg: { key: number; }) => boolean]
+>[3, arg => arg.key > 5] : [number, (arg: { key: number; }) => boolean]
+>3 : 3
+>arg => arg.key > 5 : (arg: { key: number; }) => boolean
+>arg : { key: number; }
+>arg.key > 5 : boolean
+>arg.key : number
+>arg : { key: number; }
+>key : number
+>5 : 5
+
+});
+
+type MappedReadonly<T> = {
+>MappedReadonly : MappedReadonly<T>
+
+    readonly [K in keyof T]: readonly [T[K], (arg: T) => boolean];
+>arg : T
+
+};
+
+declare function inferMappedReadonly<T>(arg: MappedReadonly<T>): void;
+>inferMappedReadonly : <T>(arg: MappedReadonly<T>) => void
+>arg : MappedReadonly<T>
+
+inferMappedReadonly({
+>inferMappedReadonly({    key: [3, arg => arg.key > 5]}) : void
+>inferMappedReadonly : <T>(arg: MappedReadonly<T>) => void
+>{    key: [3, arg => arg.key > 5]} : { key: [number, (arg: { key: number; }) => boolean]; }
+
+    key: [3, arg => arg.key > 5]
+>key : [number, (arg: { key: number; }) => boolean]
+>[3, arg => arg.key > 5] : [number, (arg: { key: number; }) => boolean]
+>3 : 3
+>arg => arg.key > 5 : (arg: { key: number; }) => boolean
+>arg : { key: number; }
+>arg.key > 5 : boolean
+>arg.key : number
+>arg : { key: number; }
+>key : number
+>5 : 5
+
+});
+
diff --git a/tests/cases/compiler/reverseMappedPartiallyInferableTypes.ts b/tests/cases/compiler/reverseMappedPartiallyInferableTypes.ts
index 799ff641c5a..5f93bfb3ac6 100644
--- a/tests/cases/compiler/reverseMappedPartiallyInferableTypes.ts
+++ b/tests/cases/compiler/reverseMappedPartiallyInferableTypes.ts
@@ -94,3 +94,35 @@ const obj3 = id({
         }
     }
 });
+
+// Repros from #40809
+
+type Mapped1<T> = {
+    [K in keyof T]: [T[K], (arg: T) => boolean];
+};
+
+declare function inferMapped1<T>(arg: Mapped1<T>): void;
+
+inferMapped1({
+    key: [3, arg => arg.key > 5]
+});
+
+type Mapped2<T> = {
+    [K in keyof T]: [T[K], unknown extends T ? unknown : (arg: T) => boolean];
+};
+
+declare function inferMapped2<T>(arg: Mapped2<T>): void;
+
+inferMapped2({
+    key: [3, arg => arg.key > 5]
+});
+
+type MappedReadonly<T> = {
+    readonly [K in keyof T]: readonly [T[K], (arg: T) => boolean];
+};
+
+declare function inferMappedReadonly<T>(arg: MappedReadonly<T>): void;
+
+inferMappedReadonly({
+    key: [3, arg => arg.key > 5]
+});