diff --git a/src/compiler/checker.ts b/src/compiler/checker.ts
index 20e6310f77..d110dfcf21 100644
--- a/src/compiler/checker.ts
+++ b/src/compiler/checker.ts
@@ -22153,7 +22153,7 @@ namespace ts {
             if (!(isTypeComparableTo(leftType, stringType) || isTypeAssignableToKind(leftType, TypeFlags.NumberLike | TypeFlags.ESSymbolLike))) {
                 error(left, Diagnostics.The_left_hand_side_of_an_in_expression_must_be_of_type_any_string_number_or_symbol);
             }
-            if (!isTypeAssignableToKind(rightType, TypeFlags.NonPrimitive | TypeFlags.InstantiableNonPrimitive)) {
+            if (!allTypesAssignableToKind(rightType, TypeFlags.NonPrimitive | TypeFlags.InstantiableNonPrimitive)) {
                 error(right, Diagnostics.The_right_hand_side_of_an_in_expression_must_be_of_type_any_an_object_type_or_a_type_parameter);
             }
             return booleanType;
diff --git a/tests/baselines/reference/inOperatorWithValidOperands.js b/tests/baselines/reference/inOperatorWithValidOperands.js
index 561abbe340..f01380b35d 100644
--- a/tests/baselines/reference/inOperatorWithValidOperands.js
+++ b/tests/baselines/reference/inOperatorWithValidOperands.js
@@ -23,6 +23,14 @@ function foo<T>(t: T) {
     var rb3 = x in t;
 }
 
+function unionCase<T, U>(t: T | U) {
+    var rb4 = x in t;
+}
+
+function unionCase2<T>(t: T | object) {
+    var rb5 = x in t;
+}
+
 interface X { x: number }
 interface Y { y: number }
 
@@ -53,6 +61,12 @@ var rb2 = x in {};
 function foo(t) {
     var rb3 = x in t;
 }
+function unionCase(t) {
+    var rb4 = x in t;
+}
+function unionCase2(t) {
+    var rb5 = x in t;
+}
 var c1;
 var c2;
 var c3;
diff --git a/tests/baselines/reference/inOperatorWithValidOperands.symbols b/tests/baselines/reference/inOperatorWithValidOperands.symbols
index 75e561989e..cbe0dbeef4 100644
--- a/tests/baselines/reference/inOperatorWithValidOperands.symbols
+++ b/tests/baselines/reference/inOperatorWithValidOperands.symbols
@@ -59,35 +59,61 @@ function foo<T>(t: T) {
 >t : Symbol(t, Decl(inOperatorWithValidOperands.ts, 20, 16))
 }
 
+function unionCase<T, U>(t: T | U) {
+>unionCase : Symbol(unionCase, Decl(inOperatorWithValidOperands.ts, 22, 1))
+>T : Symbol(T, Decl(inOperatorWithValidOperands.ts, 24, 19))
+>U : Symbol(U, Decl(inOperatorWithValidOperands.ts, 24, 21))
+>t : Symbol(t, Decl(inOperatorWithValidOperands.ts, 24, 25))
+>T : Symbol(T, Decl(inOperatorWithValidOperands.ts, 24, 19))
+>U : Symbol(U, Decl(inOperatorWithValidOperands.ts, 24, 21))
+
+    var rb4 = x in t;
+>rb4 : Symbol(rb4, Decl(inOperatorWithValidOperands.ts, 25, 7))
+>x : Symbol(x, Decl(inOperatorWithValidOperands.ts, 0, 3))
+>t : Symbol(t, Decl(inOperatorWithValidOperands.ts, 24, 25))
+}
+
+function unionCase2<T>(t: T | object) {
+>unionCase2 : Symbol(unionCase2, Decl(inOperatorWithValidOperands.ts, 26, 1))
+>T : Symbol(T, Decl(inOperatorWithValidOperands.ts, 28, 20))
+>t : Symbol(t, Decl(inOperatorWithValidOperands.ts, 28, 23))
+>T : Symbol(T, Decl(inOperatorWithValidOperands.ts, 28, 20))
+
+    var rb5 = x in t;
+>rb5 : Symbol(rb5, Decl(inOperatorWithValidOperands.ts, 29, 7))
+>x : Symbol(x, Decl(inOperatorWithValidOperands.ts, 0, 3))
+>t : Symbol(t, Decl(inOperatorWithValidOperands.ts, 28, 23))
+}
+
 interface X { x: number }
->X : Symbol(X, Decl(inOperatorWithValidOperands.ts, 22, 1))
->x : Symbol(X.x, Decl(inOperatorWithValidOperands.ts, 24, 13))
+>X : Symbol(X, Decl(inOperatorWithValidOperands.ts, 30, 1))
+>x : Symbol(X.x, Decl(inOperatorWithValidOperands.ts, 32, 13))
 
 interface Y { y: number }
->Y : Symbol(Y, Decl(inOperatorWithValidOperands.ts, 24, 25))
->y : Symbol(Y.y, Decl(inOperatorWithValidOperands.ts, 25, 13))
+>Y : Symbol(Y, Decl(inOperatorWithValidOperands.ts, 32, 25))
+>y : Symbol(Y.y, Decl(inOperatorWithValidOperands.ts, 33, 13))
 
 var c1: X | Y;
->c1 : Symbol(c1, Decl(inOperatorWithValidOperands.ts, 27, 3))
->X : Symbol(X, Decl(inOperatorWithValidOperands.ts, 22, 1))
->Y : Symbol(Y, Decl(inOperatorWithValidOperands.ts, 24, 25))
+>c1 : Symbol(c1, Decl(inOperatorWithValidOperands.ts, 35, 3))
+>X : Symbol(X, Decl(inOperatorWithValidOperands.ts, 30, 1))
+>Y : Symbol(Y, Decl(inOperatorWithValidOperands.ts, 32, 25))
 
 var c2: X;
->c2 : Symbol(c2, Decl(inOperatorWithValidOperands.ts, 28, 3))
->X : Symbol(X, Decl(inOperatorWithValidOperands.ts, 22, 1))
+>c2 : Symbol(c2, Decl(inOperatorWithValidOperands.ts, 36, 3))
+>X : Symbol(X, Decl(inOperatorWithValidOperands.ts, 30, 1))
 
 var c3: Y;
->c3 : Symbol(c3, Decl(inOperatorWithValidOperands.ts, 29, 3))
->Y : Symbol(Y, Decl(inOperatorWithValidOperands.ts, 24, 25))
+>c3 : Symbol(c3, Decl(inOperatorWithValidOperands.ts, 37, 3))
+>Y : Symbol(Y, Decl(inOperatorWithValidOperands.ts, 32, 25))
 
 var rc1 = x in c1;
->rc1 : Symbol(rc1, Decl(inOperatorWithValidOperands.ts, 31, 3))
+>rc1 : Symbol(rc1, Decl(inOperatorWithValidOperands.ts, 39, 3))
 >x : Symbol(x, Decl(inOperatorWithValidOperands.ts, 0, 3))
->c1 : Symbol(c1, Decl(inOperatorWithValidOperands.ts, 27, 3))
+>c1 : Symbol(c1, Decl(inOperatorWithValidOperands.ts, 35, 3))
 
 var rc2 = x in (c2 || c3);
->rc2 : Symbol(rc2, Decl(inOperatorWithValidOperands.ts, 32, 3))
+>rc2 : Symbol(rc2, Decl(inOperatorWithValidOperands.ts, 40, 3))
 >x : Symbol(x, Decl(inOperatorWithValidOperands.ts, 0, 3))
->c2 : Symbol(c2, Decl(inOperatorWithValidOperands.ts, 28, 3))
->c3 : Symbol(c3, Decl(inOperatorWithValidOperands.ts, 29, 3))
+>c2 : Symbol(c2, Decl(inOperatorWithValidOperands.ts, 36, 3))
+>c3 : Symbol(c3, Decl(inOperatorWithValidOperands.ts, 37, 3))
 
diff --git a/tests/baselines/reference/inOperatorWithValidOperands.types b/tests/baselines/reference/inOperatorWithValidOperands.types
index 01d6c78b1f..597454605c 100644
--- a/tests/baselines/reference/inOperatorWithValidOperands.types
+++ b/tests/baselines/reference/inOperatorWithValidOperands.types
@@ -68,6 +68,28 @@ function foo<T>(t: T) {
 >t : T
 }
 
+function unionCase<T, U>(t: T | U) {
+>unionCase : <T, U>(t: T | U) => void
+>t : T | U
+
+    var rb4 = x in t;
+>rb4 : boolean
+>x in t : boolean
+>x : any
+>t : T | U
+}
+
+function unionCase2<T>(t: T | object) {
+>unionCase2 : <T>(t: object | T) => void
+>t : object | T
+
+    var rb5 = x in t;
+>rb5 : boolean
+>x in t : boolean
+>x : any
+>t : object | T
+}
+
 interface X { x: number }
 >x : number
 
diff --git a/tests/cases/conformance/expressions/binaryOperators/inOperator/inOperatorWithValidOperands.ts b/tests/cases/conformance/expressions/binaryOperators/inOperator/inOperatorWithValidOperands.ts
index a4cdfd00a6..738edca2bc 100644
--- a/tests/cases/conformance/expressions/binaryOperators/inOperator/inOperatorWithValidOperands.ts
+++ b/tests/cases/conformance/expressions/binaryOperators/inOperator/inOperatorWithValidOperands.ts
@@ -22,6 +22,14 @@ function foo<T>(t: T) {
     var rb3 = x in t;
 }
 
+function unionCase<T, U>(t: T | U) {
+    var rb4 = x in t;
+}
+
+function unionCase2<T>(t: T | object) {
+    var rb5 = x in t;
+}
+
 interface X { x: number }
 interface Y { y: number }