diff --git a/src/compiler/checker.ts b/src/compiler/checker.ts
index 3a6d58db31c..34c18f59d06 100644
--- a/src/compiler/checker.ts
+++ b/src/compiler/checker.ts
@@ -15780,9 +15780,6 @@ namespace ts {
 
             function getTypeAtSwitchClause(flow: FlowSwitchClause): FlowType {
                 const expr = flow.switchStatement.expression;
-                if (containsMatchingReferenceDiscriminant(reference, expr)) {
-                    return declaredType;
-                }
                 const flowType = getTypeAtFlowNode(flow.antecedent);
                 let type = getTypeFromFlowType(flowType);
                 if (isMatchingReference(reference, expr)) {
@@ -15797,6 +15794,9 @@ namespace ts {
                 else if (expr.kind === SyntaxKind.TypeOfExpression && isMatchingReference(reference, (expr as TypeOfExpression).expression)) {
                     type = narrowBySwitchOnTypeOf(type, flow.switchStatement, flow.clauseStart, flow.clauseEnd);
                 }
+                else if (containsMatchingReferenceDiscriminant(reference, expr)) {
+                    type = declaredType;
+                }
                 return createFlowType(type, isIncomplete(flowType));
             }
 
diff --git a/tests/baselines/reference/discriminantPropertyCheck.errors.txt b/tests/baselines/reference/discriminantPropertyCheck.errors.txt
index 313116edde5..962faaa740e 100644
--- a/tests/baselines/reference/discriminantPropertyCheck.errors.txt
+++ b/tests/baselines/reference/discriminantPropertyCheck.errors.txt
@@ -128,4 +128,58 @@ tests/cases/compiler/discriminantPropertyCheck.ts(65,9): error TS2532: Object is
     u.a && u.b && f(u.a, u.b);
     
     u.b && u.a && f(u.a, u.b);
+    
+    // Repro from #29012
+    
+    type Additive = '+' | '-';
+    type Multiplicative = '*' | '/';
+    
+    interface AdditiveObj {
+        key: Additive
+    }
+    
+    interface MultiplicativeObj {
+        key: Multiplicative
+    }
+    
+    type Obj = AdditiveObj | MultiplicativeObj
+    
+    export function foo(obj: Obj) {
+        switch (obj.key) {
+            case '+': {
+                onlyPlus(obj.key);
+                return;
+            }
+        }
+    }
+    
+    function onlyPlus(arg: '+') {
+      return arg;
+    }
+    
+    // Repro from #29496
+    
+    declare function never(value: never): never;
+    
+    const enum BarEnum {
+        bar1 = 1,
+        bar2 = 2,
+    }
+    
+    type UnionOfBar = TypeBar1 | TypeBar2;
+    type TypeBar1 = { type: BarEnum.bar1 };
+    type TypeBar2 = { type: BarEnum.bar2 };
+    
+    function func3(value: Partial<UnionOfBar>) {
+        if (value.type !== undefined) {
+            switch (value.type) {
+                case BarEnum.bar1:
+                    break;
+                case BarEnum.bar2:
+                    break;
+                default:
+                    never(value.type);
+            }
+        }
+    }
     
\ No newline at end of file
diff --git a/tests/baselines/reference/discriminantPropertyCheck.js b/tests/baselines/reference/discriminantPropertyCheck.js
index 8b2c6f122bc..25e66e044cd 100644
--- a/tests/baselines/reference/discriminantPropertyCheck.js
+++ b/tests/baselines/reference/discriminantPropertyCheck.js
@@ -120,9 +120,65 @@ const u: U = {} as any;
 u.a && u.b && f(u.a, u.b);
 
 u.b && u.a && f(u.a, u.b);
+
+// Repro from #29012
+
+type Additive = '+' | '-';
+type Multiplicative = '*' | '/';
+
+interface AdditiveObj {
+    key: Additive
+}
+
+interface MultiplicativeObj {
+    key: Multiplicative
+}
+
+type Obj = AdditiveObj | MultiplicativeObj
+
+export function foo(obj: Obj) {
+    switch (obj.key) {
+        case '+': {
+            onlyPlus(obj.key);
+            return;
+        }
+    }
+}
+
+function onlyPlus(arg: '+') {
+  return arg;
+}
+
+// Repro from #29496
+
+declare function never(value: never): never;
+
+const enum BarEnum {
+    bar1 = 1,
+    bar2 = 2,
+}
+
+type UnionOfBar = TypeBar1 | TypeBar2;
+type TypeBar1 = { type: BarEnum.bar1 };
+type TypeBar2 = { type: BarEnum.bar2 };
+
+function func3(value: Partial<UnionOfBar>) {
+    if (value.type !== undefined) {
+        switch (value.type) {
+            case BarEnum.bar1:
+                break;
+            case BarEnum.bar2:
+                break;
+            default:
+                never(value.type);
+        }
+    }
+}
 
 
 //// [discriminantPropertyCheck.js]
+"use strict";
+exports.__esModule = true;
 function goo1(x) {
     if (x.kind === "A" && x.foo !== undefined) {
         x.foo.length;
@@ -188,3 +244,27 @@ var f = function (_a, _b) { };
 var u = {};
 u.a && u.b && f(u.a, u.b);
 u.b && u.a && f(u.a, u.b);
+function foo(obj) {
+    switch (obj.key) {
+        case '+': {
+            onlyPlus(obj.key);
+            return;
+        }
+    }
+}
+exports.foo = foo;
+function onlyPlus(arg) {
+    return arg;
+}
+function func3(value) {
+    if (value.type !== undefined) {
+        switch (value.type) {
+            case 1 /* bar1 */:
+                break;
+            case 2 /* bar2 */:
+                break;
+            default:
+                never(value.type);
+        }
+    }
+}
diff --git a/tests/baselines/reference/discriminantPropertyCheck.symbols b/tests/baselines/reference/discriminantPropertyCheck.symbols
index 78884eaf69f..b02a8113d46 100644
--- a/tests/baselines/reference/discriminantPropertyCheck.symbols
+++ b/tests/baselines/reference/discriminantPropertyCheck.symbols
@@ -377,3 +377,134 @@ u.b && u.a && f(u.a, u.b);
 >u : Symbol(u, Decl(discriminantPropertyCheck.ts, 116, 5))
 >b : Symbol(b, Decl(discriminantPropertyCheck.ts, 105, 13), Decl(discriminantPropertyCheck.ts, 110, 12))
 
+// Repro from #29012
+
+type Additive = '+' | '-';
+>Additive : Symbol(Additive, Decl(discriminantPropertyCheck.ts, 120, 26))
+
+type Multiplicative = '*' | '/';
+>Multiplicative : Symbol(Multiplicative, Decl(discriminantPropertyCheck.ts, 124, 26))
+
+interface AdditiveObj {
+>AdditiveObj : Symbol(AdditiveObj, Decl(discriminantPropertyCheck.ts, 125, 32))
+
+    key: Additive
+>key : Symbol(AdditiveObj.key, Decl(discriminantPropertyCheck.ts, 127, 23))
+>Additive : Symbol(Additive, Decl(discriminantPropertyCheck.ts, 120, 26))
+}
+
+interface MultiplicativeObj {
+>MultiplicativeObj : Symbol(MultiplicativeObj, Decl(discriminantPropertyCheck.ts, 129, 1))
+
+    key: Multiplicative
+>key : Symbol(MultiplicativeObj.key, Decl(discriminantPropertyCheck.ts, 131, 29))
+>Multiplicative : Symbol(Multiplicative, Decl(discriminantPropertyCheck.ts, 124, 26))
+}
+
+type Obj = AdditiveObj | MultiplicativeObj
+>Obj : Symbol(Obj, Decl(discriminantPropertyCheck.ts, 133, 1))
+>AdditiveObj : Symbol(AdditiveObj, Decl(discriminantPropertyCheck.ts, 125, 32))
+>MultiplicativeObj : Symbol(MultiplicativeObj, Decl(discriminantPropertyCheck.ts, 129, 1))
+
+export function foo(obj: Obj) {
+>foo : Symbol(foo, Decl(discriminantPropertyCheck.ts, 135, 42))
+>obj : Symbol(obj, Decl(discriminantPropertyCheck.ts, 137, 20))
+>Obj : Symbol(Obj, Decl(discriminantPropertyCheck.ts, 133, 1))
+
+    switch (obj.key) {
+>obj.key : Symbol(key, Decl(discriminantPropertyCheck.ts, 127, 23), Decl(discriminantPropertyCheck.ts, 131, 29))
+>obj : Symbol(obj, Decl(discriminantPropertyCheck.ts, 137, 20))
+>key : Symbol(key, Decl(discriminantPropertyCheck.ts, 127, 23), Decl(discriminantPropertyCheck.ts, 131, 29))
+
+        case '+': {
+            onlyPlus(obj.key);
+>onlyPlus : Symbol(onlyPlus, Decl(discriminantPropertyCheck.ts, 144, 1))
+>obj.key : Symbol(AdditiveObj.key, Decl(discriminantPropertyCheck.ts, 127, 23))
+>obj : Symbol(obj, Decl(discriminantPropertyCheck.ts, 137, 20))
+>key : Symbol(AdditiveObj.key, Decl(discriminantPropertyCheck.ts, 127, 23))
+
+            return;
+        }
+    }
+}
+
+function onlyPlus(arg: '+') {
+>onlyPlus : Symbol(onlyPlus, Decl(discriminantPropertyCheck.ts, 144, 1))
+>arg : Symbol(arg, Decl(discriminantPropertyCheck.ts, 146, 18))
+
+  return arg;
+>arg : Symbol(arg, Decl(discriminantPropertyCheck.ts, 146, 18))
+}
+
+// Repro from #29496
+
+declare function never(value: never): never;
+>never : Symbol(never, Decl(discriminantPropertyCheck.ts, 148, 1))
+>value : Symbol(value, Decl(discriminantPropertyCheck.ts, 152, 23))
+
+const enum BarEnum {
+>BarEnum : Symbol(BarEnum, Decl(discriminantPropertyCheck.ts, 152, 44))
+
+    bar1 = 1,
+>bar1 : Symbol(BarEnum.bar1, Decl(discriminantPropertyCheck.ts, 154, 20))
+
+    bar2 = 2,
+>bar2 : Symbol(BarEnum.bar2, Decl(discriminantPropertyCheck.ts, 155, 13))
+}
+
+type UnionOfBar = TypeBar1 | TypeBar2;
+>UnionOfBar : Symbol(UnionOfBar, Decl(discriminantPropertyCheck.ts, 157, 1))
+>TypeBar1 : Symbol(TypeBar1, Decl(discriminantPropertyCheck.ts, 159, 38))
+>TypeBar2 : Symbol(TypeBar2, Decl(discriminantPropertyCheck.ts, 160, 39))
+
+type TypeBar1 = { type: BarEnum.bar1 };
+>TypeBar1 : Symbol(TypeBar1, Decl(discriminantPropertyCheck.ts, 159, 38))
+>type : Symbol(type, Decl(discriminantPropertyCheck.ts, 160, 17))
+>BarEnum : Symbol(BarEnum, Decl(discriminantPropertyCheck.ts, 152, 44))
+>bar1 : Symbol(BarEnum.bar1, Decl(discriminantPropertyCheck.ts, 154, 20))
+
+type TypeBar2 = { type: BarEnum.bar2 };
+>TypeBar2 : Symbol(TypeBar2, Decl(discriminantPropertyCheck.ts, 160, 39))
+>type : Symbol(type, Decl(discriminantPropertyCheck.ts, 161, 17))
+>BarEnum : Symbol(BarEnum, Decl(discriminantPropertyCheck.ts, 152, 44))
+>bar2 : Symbol(BarEnum.bar2, Decl(discriminantPropertyCheck.ts, 155, 13))
+
+function func3(value: Partial<UnionOfBar>) {
+>func3 : Symbol(func3, Decl(discriminantPropertyCheck.ts, 161, 39))
+>value : Symbol(value, Decl(discriminantPropertyCheck.ts, 163, 15))
+>Partial : Symbol(Partial, Decl(lib.es5.d.ts, --, --))
+>UnionOfBar : Symbol(UnionOfBar, Decl(discriminantPropertyCheck.ts, 157, 1))
+
+    if (value.type !== undefined) {
+>value.type : Symbol(type, Decl(discriminantPropertyCheck.ts, 160, 17), Decl(discriminantPropertyCheck.ts, 161, 17))
+>value : Symbol(value, Decl(discriminantPropertyCheck.ts, 163, 15))
+>type : Symbol(type, Decl(discriminantPropertyCheck.ts, 160, 17), Decl(discriminantPropertyCheck.ts, 161, 17))
+>undefined : Symbol(undefined)
+
+        switch (value.type) {
+>value.type : Symbol(type, Decl(discriminantPropertyCheck.ts, 160, 17), Decl(discriminantPropertyCheck.ts, 161, 17))
+>value : Symbol(value, Decl(discriminantPropertyCheck.ts, 163, 15))
+>type : Symbol(type, Decl(discriminantPropertyCheck.ts, 160, 17), Decl(discriminantPropertyCheck.ts, 161, 17))
+
+            case BarEnum.bar1:
+>BarEnum.bar1 : Symbol(BarEnum.bar1, Decl(discriminantPropertyCheck.ts, 154, 20))
+>BarEnum : Symbol(BarEnum, Decl(discriminantPropertyCheck.ts, 152, 44))
+>bar1 : Symbol(BarEnum.bar1, Decl(discriminantPropertyCheck.ts, 154, 20))
+
+                break;
+            case BarEnum.bar2:
+>BarEnum.bar2 : Symbol(BarEnum.bar2, Decl(discriminantPropertyCheck.ts, 155, 13))
+>BarEnum : Symbol(BarEnum, Decl(discriminantPropertyCheck.ts, 152, 44))
+>bar2 : Symbol(BarEnum.bar2, Decl(discriminantPropertyCheck.ts, 155, 13))
+
+                break;
+            default:
+                never(value.type);
+>never : Symbol(never, Decl(discriminantPropertyCheck.ts, 148, 1))
+>value.type : Symbol(type, Decl(discriminantPropertyCheck.ts, 160, 17), Decl(discriminantPropertyCheck.ts, 161, 17))
+>value : Symbol(value, Decl(discriminantPropertyCheck.ts, 163, 15))
+>type : Symbol(type, Decl(discriminantPropertyCheck.ts, 160, 17), Decl(discriminantPropertyCheck.ts, 161, 17))
+        }
+    }
+}
+
diff --git a/tests/baselines/reference/discriminantPropertyCheck.types b/tests/baselines/reference/discriminantPropertyCheck.types
index c243ef5e798..def89e7be1f 100644
--- a/tests/baselines/reference/discriminantPropertyCheck.types
+++ b/tests/baselines/reference/discriminantPropertyCheck.types
@@ -378,3 +378,126 @@ u.b && u.a && f(u.a, u.b);
 >u : U
 >b : string
 
+// Repro from #29012
+
+type Additive = '+' | '-';
+>Additive : Additive
+
+type Multiplicative = '*' | '/';
+>Multiplicative : Multiplicative
+
+interface AdditiveObj {
+    key: Additive
+>key : Additive
+}
+
+interface MultiplicativeObj {
+    key: Multiplicative
+>key : Multiplicative
+}
+
+type Obj = AdditiveObj | MultiplicativeObj
+>Obj : Obj
+
+export function foo(obj: Obj) {
+>foo : (obj: Obj) => void
+>obj : Obj
+
+    switch (obj.key) {
+>obj.key : "+" | "-" | "*" | "/"
+>obj : Obj
+>key : "+" | "-" | "*" | "/"
+
+        case '+': {
+>'+' : "+"
+
+            onlyPlus(obj.key);
+>onlyPlus(obj.key) : "+"
+>onlyPlus : (arg: "+") => "+"
+>obj.key : "+"
+>obj : AdditiveObj
+>key : "+"
+
+            return;
+        }
+    }
+}
+
+function onlyPlus(arg: '+') {
+>onlyPlus : (arg: "+") => "+"
+>arg : "+"
+
+  return arg;
+>arg : "+"
+}
+
+// Repro from #29496
+
+declare function never(value: never): never;
+>never : (value: never) => never
+>value : never
+
+const enum BarEnum {
+>BarEnum : BarEnum
+
+    bar1 = 1,
+>bar1 : BarEnum.bar1
+>1 : 1
+
+    bar2 = 2,
+>bar2 : BarEnum.bar2
+>2 : 2
+}
+
+type UnionOfBar = TypeBar1 | TypeBar2;
+>UnionOfBar : UnionOfBar
+
+type TypeBar1 = { type: BarEnum.bar1 };
+>TypeBar1 : TypeBar1
+>type : BarEnum.bar1
+>BarEnum : any
+
+type TypeBar2 = { type: BarEnum.bar2 };
+>TypeBar2 : TypeBar2
+>type : BarEnum.bar2
+>BarEnum : any
+
+function func3(value: Partial<UnionOfBar>) {
+>func3 : (value: Partial<TypeBar1> | Partial<TypeBar2>) => void
+>value : Partial<TypeBar1> | Partial<TypeBar2>
+
+    if (value.type !== undefined) {
+>value.type !== undefined : boolean
+>value.type : BarEnum | undefined
+>value : Partial<TypeBar1> | Partial<TypeBar2>
+>type : BarEnum | undefined
+>undefined : undefined
+
+        switch (value.type) {
+>value.type : BarEnum
+>value : Partial<TypeBar1> | Partial<TypeBar2>
+>type : BarEnum
+
+            case BarEnum.bar1:
+>BarEnum.bar1 : BarEnum.bar1
+>BarEnum : typeof BarEnum
+>bar1 : BarEnum.bar1
+
+                break;
+            case BarEnum.bar2:
+>BarEnum.bar2 : BarEnum.bar2
+>BarEnum : typeof BarEnum
+>bar2 : BarEnum.bar2
+
+                break;
+            default:
+                never(value.type);
+>never(value.type) : never
+>never : (value: never) => never
+>value.type : never
+>value : Partial<TypeBar1> | Partial<TypeBar2>
+>type : never
+        }
+    }
+}
+
diff --git a/tests/cases/compiler/discriminantPropertyCheck.ts b/tests/cases/compiler/discriminantPropertyCheck.ts
index a24fe07973b..6a15af5db65 100644
--- a/tests/cases/compiler/discriminantPropertyCheck.ts
+++ b/tests/cases/compiler/discriminantPropertyCheck.ts
@@ -121,3 +121,57 @@ const u: U = {} as any;
 u.a && u.b && f(u.a, u.b);
 
 u.b && u.a && f(u.a, u.b);
+
+// Repro from #29012
+
+type Additive = '+' | '-';
+type Multiplicative = '*' | '/';
+
+interface AdditiveObj {
+    key: Additive
+}
+
+interface MultiplicativeObj {
+    key: Multiplicative
+}
+
+type Obj = AdditiveObj | MultiplicativeObj
+
+export function foo(obj: Obj) {
+    switch (obj.key) {
+        case '+': {
+            onlyPlus(obj.key);
+            return;
+        }
+    }
+}
+
+function onlyPlus(arg: '+') {
+  return arg;
+}
+
+// Repro from #29496
+
+declare function never(value: never): never;
+
+const enum BarEnum {
+    bar1 = 1,
+    bar2 = 2,
+}
+
+type UnionOfBar = TypeBar1 | TypeBar2;
+type TypeBar1 = { type: BarEnum.bar1 };
+type TypeBar2 = { type: BarEnum.bar2 };
+
+function func3(value: Partial<UnionOfBar>) {
+    if (value.type !== undefined) {
+        switch (value.type) {
+            case BarEnum.bar1:
+                break;
+            case BarEnum.bar2:
+                break;
+            default:
+                never(value.type);
+        }
+    }
+}