diff --git a/src/compiler/checker.ts b/src/compiler/checker.ts
index d8f95d86662..a745a384128 100644
--- a/src/compiler/checker.ts
+++ b/src/compiler/checker.ts
@@ -7991,7 +7991,7 @@ namespace ts {
             }
             if (!(indexType.flags & TypeFlags.Nullable) && isTypeAssignableToKind(indexType, TypeFlags.StringLike | TypeFlags.NumberLike | TypeFlags.ESSymbolLike)) {
                 if (isTypeAny(objectType)) {
-                    return anyType;
+                    return objectType;
                 }
                 const indexInfo = isTypeAssignableToKind(indexType, TypeFlags.NumberLike) && getIndexInfoOfType(objectType, IndexKind.Number) ||
                     getIndexInfoOfType(objectType, IndexKind.String) ||
diff --git a/tests/baselines/reference/conditionalTypes1.errors.txt b/tests/baselines/reference/conditionalTypes1.errors.txt
index b79ec721e97..869e740ad1a 100644
--- a/tests/baselines/reference/conditionalTypes1.errors.txt
+++ b/tests/baselines/reference/conditionalTypes1.errors.txt
@@ -436,4 +436,15 @@ tests/cases/conformance/types/conditional/conditionalTypes1.ts(275,43): error TS
                                               ~~~~~
 !!! error TS2322: Type 'T95<U>' is not assignable to type 'T94<U>'.
 !!! error TS2322:   Type 'boolean' is not assignable to type 'true'.
+    
+    // Repro from #21863
+    
+    function f50() {
+        type Eq<T, U> = T extends U ? U extends T ? true : false : false;
+        type If<S, T, U> = S extends false ? U : T;
+        type Omit<T extends object> = { [P in keyof T]: If<Eq<T[P], never>, never, P>; }[keyof T];
+        type Omit2<T extends object, U = never> = { [P in keyof T]: If<Eq<T[P], U>, never, P>; }[keyof T];
+        type A = Omit<{ a: void; b: never; }>;  // 'a'
+        type B = Omit2<{ a: void; b: never; }>;  // 'a'
+    }
     
\ No newline at end of file
diff --git a/tests/baselines/reference/conditionalTypes1.js b/tests/baselines/reference/conditionalTypes1.js
index fe617d777ca..9020774d7fe 100644
--- a/tests/baselines/reference/conditionalTypes1.js
+++ b/tests/baselines/reference/conditionalTypes1.js
@@ -274,6 +274,17 @@ type T94<T> = T extends string ? true : 42;
 type T95<T> = T extends string ? boolean : number;
 const f44 = <U>(value: T94<U>): T95<U> => value;
 const f45 = <U>(value: T95<U>): T94<U> => value;  // Error
+
+// Repro from #21863
+
+function f50() {
+    type Eq<T, U> = T extends U ? U extends T ? true : false : false;
+    type If<S, T, U> = S extends false ? U : T;
+    type Omit<T extends object> = { [P in keyof T]: If<Eq<T[P], never>, never, P>; }[keyof T];
+    type Omit2<T extends object, U = never> = { [P in keyof T]: If<Eq<T[P], U>, never, P>; }[keyof T];
+    type A = Omit<{ a: void; b: never; }>;  // 'a'
+    type B = Omit2<{ a: void; b: never; }>;  // 'a'
+}
 
 
 //// [conditionalTypes1.js]
@@ -361,6 +372,9 @@ var f42 = function (a) { return a; };
 var f43 = function (a) { return a; };
 var f44 = function (value) { return value; };
 var f45 = function (value) { return value; }; // Error
+// Repro from #21863
+function f50() {
+}
 
 
 //// [conditionalTypes1.d.ts]
@@ -546,3 +560,4 @@ declare type T94<T> = T extends string ? true : 42;
 declare type T95<T> = T extends string ? boolean : number;
 declare const f44: <U>(value: T94<U>) => T95<U>;
 declare const f45: <U>(value: T95<U>) => T94<U>;
+declare function f50(): void;
diff --git a/tests/baselines/reference/conditionalTypes1.symbols b/tests/baselines/reference/conditionalTypes1.symbols
index ef5dc0d58f8..6c05ee1eeee 100644
--- a/tests/baselines/reference/conditionalTypes1.symbols
+++ b/tests/baselines/reference/conditionalTypes1.symbols
@@ -1059,3 +1059,65 @@ const f45 = <U>(value: T95<U>): T94<U> => value;  // Error
 >U : Symbol(U, Decl(conditionalTypes1.ts, 274, 13))
 >value : Symbol(value, Decl(conditionalTypes1.ts, 274, 16))
 
+// Repro from #21863
+
+function f50() {
+>f50 : Symbol(f50, Decl(conditionalTypes1.ts, 274, 48))
+
+    type Eq<T, U> = T extends U ? U extends T ? true : false : false;
+>Eq : Symbol(Eq, Decl(conditionalTypes1.ts, 278, 16))
+>T : Symbol(T, Decl(conditionalTypes1.ts, 279, 12))
+>U : Symbol(U, Decl(conditionalTypes1.ts, 279, 14))
+>T : Symbol(T, Decl(conditionalTypes1.ts, 279, 12))
+>U : Symbol(U, Decl(conditionalTypes1.ts, 279, 14))
+>U : Symbol(U, Decl(conditionalTypes1.ts, 279, 14))
+>T : Symbol(T, Decl(conditionalTypes1.ts, 279, 12))
+
+    type If<S, T, U> = S extends false ? U : T;
+>If : Symbol(If, Decl(conditionalTypes1.ts, 279, 69))
+>S : Symbol(S, Decl(conditionalTypes1.ts, 280, 12))
+>T : Symbol(T, Decl(conditionalTypes1.ts, 280, 14))
+>U : Symbol(U, Decl(conditionalTypes1.ts, 280, 17))
+>S : Symbol(S, Decl(conditionalTypes1.ts, 280, 12))
+>U : Symbol(U, Decl(conditionalTypes1.ts, 280, 17))
+>T : Symbol(T, Decl(conditionalTypes1.ts, 280, 14))
+
+    type Omit<T extends object> = { [P in keyof T]: If<Eq<T[P], never>, never, P>; }[keyof T];
+>Omit : Symbol(Omit, Decl(conditionalTypes1.ts, 280, 47))
+>T : Symbol(T, Decl(conditionalTypes1.ts, 281, 14))
+>P : Symbol(P, Decl(conditionalTypes1.ts, 281, 37))
+>T : Symbol(T, Decl(conditionalTypes1.ts, 281, 14))
+>If : Symbol(If, Decl(conditionalTypes1.ts, 279, 69))
+>Eq : Symbol(Eq, Decl(conditionalTypes1.ts, 278, 16))
+>T : Symbol(T, Decl(conditionalTypes1.ts, 281, 14))
+>P : Symbol(P, Decl(conditionalTypes1.ts, 281, 37))
+>P : Symbol(P, Decl(conditionalTypes1.ts, 281, 37))
+>T : Symbol(T, Decl(conditionalTypes1.ts, 281, 14))
+
+    type Omit2<T extends object, U = never> = { [P in keyof T]: If<Eq<T[P], U>, never, P>; }[keyof T];
+>Omit2 : Symbol(Omit2, Decl(conditionalTypes1.ts, 281, 94))
+>T : Symbol(T, Decl(conditionalTypes1.ts, 282, 15))
+>U : Symbol(U, Decl(conditionalTypes1.ts, 282, 32))
+>P : Symbol(P, Decl(conditionalTypes1.ts, 282, 49))
+>T : Symbol(T, Decl(conditionalTypes1.ts, 282, 15))
+>If : Symbol(If, Decl(conditionalTypes1.ts, 279, 69))
+>Eq : Symbol(Eq, Decl(conditionalTypes1.ts, 278, 16))
+>T : Symbol(T, Decl(conditionalTypes1.ts, 282, 15))
+>P : Symbol(P, Decl(conditionalTypes1.ts, 282, 49))
+>U : Symbol(U, Decl(conditionalTypes1.ts, 282, 32))
+>P : Symbol(P, Decl(conditionalTypes1.ts, 282, 49))
+>T : Symbol(T, Decl(conditionalTypes1.ts, 282, 15))
+
+    type A = Omit<{ a: void; b: never; }>;  // 'a'
+>A : Symbol(A, Decl(conditionalTypes1.ts, 282, 102))
+>Omit : Symbol(Omit, Decl(conditionalTypes1.ts, 280, 47))
+>a : Symbol(a, Decl(conditionalTypes1.ts, 283, 19))
+>b : Symbol(b, Decl(conditionalTypes1.ts, 283, 28))
+
+    type B = Omit2<{ a: void; b: never; }>;  // 'a'
+>B : Symbol(B, Decl(conditionalTypes1.ts, 283, 42))
+>Omit2 : Symbol(Omit2, Decl(conditionalTypes1.ts, 281, 94))
+>a : Symbol(a, Decl(conditionalTypes1.ts, 284, 20))
+>b : Symbol(b, Decl(conditionalTypes1.ts, 284, 29))
+}
+
diff --git a/tests/baselines/reference/conditionalTypes1.types b/tests/baselines/reference/conditionalTypes1.types
index b915b8438d0..b544acdf3e2 100644
--- a/tests/baselines/reference/conditionalTypes1.types
+++ b/tests/baselines/reference/conditionalTypes1.types
@@ -1208,3 +1208,69 @@ const f45 = <U>(value: T95<U>): T94<U> => value;  // Error
 >U : U
 >value : T95<U>
 
+// Repro from #21863
+
+function f50() {
+>f50 : () => void
+
+    type Eq<T, U> = T extends U ? U extends T ? true : false : false;
+>Eq : T extends U ? U extends T ? true : false : false
+>T : T
+>U : U
+>T : T
+>U : U
+>U : U
+>T : T
+>true : true
+>false : false
+>false : false
+
+    type If<S, T, U> = S extends false ? U : T;
+>If : S extends false ? U : T
+>S : S
+>T : T
+>U : U
+>S : S
+>false : false
+>U : U
+>T : T
+
+    type Omit<T extends object> = { [P in keyof T]: If<Eq<T[P], never>, never, P>; }[keyof T];
+>Omit : { [P in keyof T]: (T[P] extends never ? boolean : false) extends false ? P : never; }[keyof T]
+>T : T
+>P : P
+>T : T
+>If : S extends false ? U : T
+>Eq : T extends U ? U extends T ? true : false : false
+>T : T
+>P : P
+>P : P
+>T : T
+
+    type Omit2<T extends object, U = never> = { [P in keyof T]: If<Eq<T[P], U>, never, P>; }[keyof T];
+>Omit2 : { [P in keyof T]: (T[P] extends U ? U extends T[P] ? true : false : false) extends false ? P : never; }[keyof T]
+>T : T
+>U : U
+>P : P
+>T : T
+>If : S extends false ? U : T
+>Eq : T extends U ? U extends T ? true : false : false
+>T : T
+>P : P
+>U : U
+>P : P
+>T : T
+
+    type A = Omit<{ a: void; b: never; }>;  // 'a'
+>A : "a"
+>Omit : { [P in keyof T]: (T[P] extends never ? boolean : false) extends false ? P : never; }[keyof T]
+>a : void
+>b : never
+
+    type B = Omit2<{ a: void; b: never; }>;  // 'a'
+>B : "a"
+>Omit2 : { [P in keyof T]: (T[P] extends U ? U extends T[P] ? true : false : false) extends false ? P : never; }[keyof T]
+>a : void
+>b : never
+}
+
diff --git a/tests/cases/conformance/types/conditional/conditionalTypes1.ts b/tests/cases/conformance/types/conditional/conditionalTypes1.ts
index 10cfceb0132..94a802a0ffc 100644
--- a/tests/cases/conformance/types/conditional/conditionalTypes1.ts
+++ b/tests/cases/conformance/types/conditional/conditionalTypes1.ts
@@ -276,3 +276,14 @@ type T94<T> = T extends string ? true : 42;
 type T95<T> = T extends string ? boolean : number;
 const f44 = <U>(value: T94<U>): T95<U> => value;
 const f45 = <U>(value: T95<U>): T94<U> => value;  // Error
+
+// Repro from #21863
+
+function f50() {
+    type Eq<T, U> = T extends U ? U extends T ? true : false : false;
+    type If<S, T, U> = S extends false ? U : T;
+    type Omit<T extends object> = { [P in keyof T]: If<Eq<T[P], never>, never, P>; }[keyof T];
+    type Omit2<T extends object, U = never> = { [P in keyof T]: If<Eq<T[P], U>, never, P>; }[keyof T];
+    type A = Omit<{ a: void; b: never; }>;  // 'a'
+    type B = Omit2<{ a: void; b: never; }>;  // 'a'
+}