diff --git a/src/compiler/checker.ts b/src/compiler/checker.ts
index 6d8d084acc580..55b7c9113c97f 100644
--- a/src/compiler/checker.ts
+++ b/src/compiler/checker.ts
@@ -8008,10 +8008,10 @@ namespace ts {
         }
 
         function getLiteralTypeFromPropertyName(prop: Symbol) {
-            const links = getSymbolLinks(prop);
+            const links = getSymbolLinks(getLateBoundSymbol(prop));
             if (!links.nameType) {
                 if (links.target) {
-                    Debug.assert(links.target.escapedName === prop.escapedName, "Target symbol and symbol do not have the same name");
+                    Debug.assert(links.target.escapedName === prop.escapedName || links.target.escapedName === InternalSymbolName.Computed, "Target symbol and symbol do not have the same name");
                     links.nameType = getLiteralTypeFromPropertyName(links.target);
                 }
                 else {
@@ -10558,6 +10558,11 @@ namespace ts {
                     if (isIgnoredJsxProperty(source, prop, /*targetMemberType*/ undefined)) {
                         continue;
                     }
+                    // Skip over symbol-named members
+                    const nameType = getLiteralTypeFromPropertyName(prop);
+                    if (nameType !== undefined && !(isRelatedTo(nameType, stringType) || isRelatedTo(nameType, numberType))) {
+                        continue;
+                    }
                     if (kind === IndexKind.String || isNumericLiteralName(prop.escapedName)) {
                         const related = isRelatedTo(getTypeOfSymbol(prop), target, reportErrors);
                         if (!related) {
diff --git a/tests/baselines/reference/uniqueSymbolAllowsIndexInObjectWithIndexSignature.errors.txt b/tests/baselines/reference/uniqueSymbolAllowsIndexInObjectWithIndexSignature.errors.txt
new file mode 100644
index 0000000000000..eca289e819344
--- /dev/null
+++ b/tests/baselines/reference/uniqueSymbolAllowsIndexInObjectWithIndexSignature.errors.txt
@@ -0,0 +1,21 @@
+tests/cases/compiler/uniqueSymbolAllowsIndexInObjectWithIndexSignature.ts(10,5): error TS2322: Type '{ [SYM]: "str"; }' is not assignable to type 'I'.
+  Types of property '[SYM]' are incompatible.
+    Type '"str"' is not assignable to type '"sym"'.
+
+
+==== tests/cases/compiler/uniqueSymbolAllowsIndexInObjectWithIndexSignature.ts (1 errors) ====
+    // https://github.com/Microsoft/TypeScript/issues/21962
+    export const SYM = Symbol('a unique symbol');
+    
+    export interface I {
+      [SYM]: 'sym';
+      [x: string]: 'str';
+    }
+    
+    let a: I = {[SYM]: 'sym'}; // Expect ok
+    let b: I = {[SYM]: 'str'}; // Expect error
+        ~
+!!! error TS2322: Type '{ [SYM]: "str"; }' is not assignable to type 'I'.
+!!! error TS2322:   Types of property '[SYM]' are incompatible.
+!!! error TS2322:     Type '"str"' is not assignable to type '"sym"'.
+    
\ No newline at end of file
diff --git a/tests/baselines/reference/uniqueSymbolAllowsIndexInObjectWithIndexSignature.js b/tests/baselines/reference/uniqueSymbolAllowsIndexInObjectWithIndexSignature.js
new file mode 100644
index 0000000000000..21a6d85ac2387
--- /dev/null
+++ b/tests/baselines/reference/uniqueSymbolAllowsIndexInObjectWithIndexSignature.js
@@ -0,0 +1,21 @@
+//// [uniqueSymbolAllowsIndexInObjectWithIndexSignature.ts]
+// https://github.com/Microsoft/TypeScript/issues/21962
+export const SYM = Symbol('a unique symbol');
+
+export interface I {
+  [SYM]: 'sym';
+  [x: string]: 'str';
+}
+
+let a: I = {[SYM]: 'sym'}; // Expect ok
+let b: I = {[SYM]: 'str'}; // Expect error
+
+
+//// [uniqueSymbolAllowsIndexInObjectWithIndexSignature.js]
+"use strict";
+exports.__esModule = true;
+// https://github.com/Microsoft/TypeScript/issues/21962
+exports.SYM = Symbol('a unique symbol');
+var a = (_a = {}, _a[exports.SYM] = 'sym', _a); // Expect ok
+var b = (_b = {}, _b[exports.SYM] = 'str', _b); // Expect error
+var _a, _b;
diff --git a/tests/baselines/reference/uniqueSymbolAllowsIndexInObjectWithIndexSignature.symbols b/tests/baselines/reference/uniqueSymbolAllowsIndexInObjectWithIndexSignature.symbols
new file mode 100644
index 0000000000000..fc3ba1ced5b17
--- /dev/null
+++ b/tests/baselines/reference/uniqueSymbolAllowsIndexInObjectWithIndexSignature.symbols
@@ -0,0 +1,29 @@
+=== tests/cases/compiler/uniqueSymbolAllowsIndexInObjectWithIndexSignature.ts ===
+// https://github.com/Microsoft/TypeScript/issues/21962
+export const SYM = Symbol('a unique symbol');
+>SYM : Symbol(SYM, Decl(uniqueSymbolAllowsIndexInObjectWithIndexSignature.ts, 1, 12))
+>Symbol : Symbol(Symbol, Decl(lib.es2015.symbol.wellknown.d.ts, --, --), Decl(lib.es2015.symbol.d.ts, --, --), Decl(lib.es2015.symbol.d.ts, --, --))
+
+export interface I {
+>I : Symbol(I, Decl(uniqueSymbolAllowsIndexInObjectWithIndexSignature.ts, 1, 45))
+
+  [SYM]: 'sym';
+>[SYM] : Symbol(I[SYM], Decl(uniqueSymbolAllowsIndexInObjectWithIndexSignature.ts, 3, 20))
+>SYM : Symbol(SYM, Decl(uniqueSymbolAllowsIndexInObjectWithIndexSignature.ts, 1, 12))
+
+  [x: string]: 'str';
+>x : Symbol(x, Decl(uniqueSymbolAllowsIndexInObjectWithIndexSignature.ts, 5, 3))
+}
+
+let a: I = {[SYM]: 'sym'}; // Expect ok
+>a : Symbol(a, Decl(uniqueSymbolAllowsIndexInObjectWithIndexSignature.ts, 8, 3))
+>I : Symbol(I, Decl(uniqueSymbolAllowsIndexInObjectWithIndexSignature.ts, 1, 45))
+>[SYM] : Symbol([SYM], Decl(uniqueSymbolAllowsIndexInObjectWithIndexSignature.ts, 8, 12))
+>SYM : Symbol(SYM, Decl(uniqueSymbolAllowsIndexInObjectWithIndexSignature.ts, 1, 12))
+
+let b: I = {[SYM]: 'str'}; // Expect error
+>b : Symbol(b, Decl(uniqueSymbolAllowsIndexInObjectWithIndexSignature.ts, 9, 3))
+>I : Symbol(I, Decl(uniqueSymbolAllowsIndexInObjectWithIndexSignature.ts, 1, 45))
+>[SYM] : Symbol([SYM], Decl(uniqueSymbolAllowsIndexInObjectWithIndexSignature.ts, 9, 12))
+>SYM : Symbol(SYM, Decl(uniqueSymbolAllowsIndexInObjectWithIndexSignature.ts, 1, 12))
+
diff --git a/tests/baselines/reference/uniqueSymbolAllowsIndexInObjectWithIndexSignature.types b/tests/baselines/reference/uniqueSymbolAllowsIndexInObjectWithIndexSignature.types
new file mode 100644
index 0000000000000..be4cafe5e856d
--- /dev/null
+++ b/tests/baselines/reference/uniqueSymbolAllowsIndexInObjectWithIndexSignature.types
@@ -0,0 +1,35 @@
+=== tests/cases/compiler/uniqueSymbolAllowsIndexInObjectWithIndexSignature.ts ===
+// https://github.com/Microsoft/TypeScript/issues/21962
+export const SYM = Symbol('a unique symbol');
+>SYM : unique symbol
+>Symbol('a unique symbol') : unique symbol
+>Symbol : SymbolConstructor
+>'a unique symbol' : "a unique symbol"
+
+export interface I {
+>I : I
+
+  [SYM]: 'sym';
+>[SYM] : "sym"
+>SYM : unique symbol
+
+  [x: string]: 'str';
+>x : string
+}
+
+let a: I = {[SYM]: 'sym'}; // Expect ok
+>a : I
+>I : I
+>{[SYM]: 'sym'} : { [SYM]: "sym"; }
+>[SYM] : "sym"
+>SYM : unique symbol
+>'sym' : "sym"
+
+let b: I = {[SYM]: 'str'}; // Expect error
+>b : I
+>I : I
+>{[SYM]: 'str'} : { [SYM]: "str"; }
+>[SYM] : "str"
+>SYM : unique symbol
+>'str' : "str"
+
diff --git a/tests/cases/compiler/uniqueSymbolAllowsIndexInObjectWithIndexSignature.ts b/tests/cases/compiler/uniqueSymbolAllowsIndexInObjectWithIndexSignature.ts
new file mode 100644
index 0000000000000..0550c7b8d9776
--- /dev/null
+++ b/tests/cases/compiler/uniqueSymbolAllowsIndexInObjectWithIndexSignature.ts
@@ -0,0 +1,11 @@
+// @lib: es6
+// https://github.com/Microsoft/TypeScript/issues/21962
+export const SYM = Symbol('a unique symbol');
+
+export interface I {
+  [SYM]: 'sym';
+  [x: string]: 'str';
+}
+
+let a: I = {[SYM]: 'sym'}; // Expect ok
+let b: I = {[SYM]: 'str'}; // Expect error