diff --git a/src/compiler/checker.ts b/src/compiler/checker.ts
index a4ad3af7d9a35..5a5bdc91573ec 100644
--- a/src/compiler/checker.ts
+++ b/src/compiler/checker.ts
@@ -7597,8 +7597,8 @@ namespace ts {
                         }
                     }
                     // The properties of a union type are those that are present in all constituent types, so
-                    // we only need to check the properties of the first type
-                    if (type.flags & TypeFlags.Union) {
+                    // we only need to check the properties of the first type without index signature
+                    if (type.flags & TypeFlags.Union && !getIndexInfoOfType(current, IndexKind.String) && !getIndexInfoOfType(current, IndexKind.Number)) {
                         break;
                     }
                 }
diff --git a/tests/baselines/reference/conditionalTypes2.errors.txt b/tests/baselines/reference/conditionalTypes2.errors.txt
index 4093bf46fb0ee..cf2efaf6adeec 100644
--- a/tests/baselines/reference/conditionalTypes2.errors.txt
+++ b/tests/baselines/reference/conditionalTypes2.errors.txt
@@ -14,9 +14,9 @@ tests/cases/conformance/types/conditional/conditionalTypes2.ts(24,5): error TS23
               Type 'keyof B' is not assignable to type 'number | "toString" | "charAt" | "charCodeAt" | "concat" | "indexOf" | "lastIndexOf" | "localeCompare" | "match" | "replace" | "search" | "slice" | "split" | "substring" | "toLowerCase" | "toLocaleLowerCase" | "toUpperCase" | "toLocaleUpperCase" | "trim" | "length" | "substr" | "valueOf"'.
                 Type 'string | number | symbol' is not assignable to type 'number | "toString" | "charAt" | "charCodeAt" | "concat" | "indexOf" | "lastIndexOf" | "localeCompare" | "match" | "replace" | "search" | "slice" | "split" | "substring" | "toLowerCase" | "toLocaleLowerCase" | "toUpperCase" | "toLocaleUpperCase" | "trim" | "length" | "substr" | "valueOf"'.
                   Type 'string' is not assignable to type 'number | "toString" | "charAt" | "charCodeAt" | "concat" | "indexOf" | "lastIndexOf" | "localeCompare" | "match" | "replace" | "search" | "slice" | "split" | "substring" | "toLowerCase" | "toLocaleLowerCase" | "toUpperCase" | "toLocaleUpperCase" | "trim" | "length" | "substr" | "valueOf"'.
-                    Type 'keyof B' is not assignable to type '"valueOf"'.
-                      Type 'string | number | symbol' is not assignable to type '"valueOf"'.
-                        Type 'string' is not assignable to type '"valueOf"'.
+                    Type 'keyof B' is not assignable to type 'number'.
+                      Type 'string | number | symbol' is not assignable to type 'number'.
+                        Type 'string' is not assignable to type 'number'.
 tests/cases/conformance/types/conditional/conditionalTypes2.ts(25,5): error TS2322: Type 'Invariant<A>' is not assignable to type 'Invariant<B>'.
   Types of property 'foo' are incompatible.
     Type 'A extends string ? keyof A : A' is not assignable to type 'B extends string ? keyof B : B'.
@@ -77,9 +77,9 @@ tests/cases/conformance/types/conditional/conditionalTypes2.ts(75,12): error TS2
 !!! error TS2322:               Type 'keyof B' is not assignable to type 'number | "toString" | "charAt" | "charCodeAt" | "concat" | "indexOf" | "lastIndexOf" | "localeCompare" | "match" | "replace" | "search" | "slice" | "split" | "substring" | "toLowerCase" | "toLocaleLowerCase" | "toUpperCase" | "toLocaleUpperCase" | "trim" | "length" | "substr" | "valueOf"'.
 !!! error TS2322:                 Type 'string | number | symbol' is not assignable to type 'number | "toString" | "charAt" | "charCodeAt" | "concat" | "indexOf" | "lastIndexOf" | "localeCompare" | "match" | "replace" | "search" | "slice" | "split" | "substring" | "toLowerCase" | "toLocaleLowerCase" | "toUpperCase" | "toLocaleUpperCase" | "trim" | "length" | "substr" | "valueOf"'.
 !!! error TS2322:                   Type 'string' is not assignable to type 'number | "toString" | "charAt" | "charCodeAt" | "concat" | "indexOf" | "lastIndexOf" | "localeCompare" | "match" | "replace" | "search" | "slice" | "split" | "substring" | "toLowerCase" | "toLocaleLowerCase" | "toUpperCase" | "toLocaleUpperCase" | "trim" | "length" | "substr" | "valueOf"'.
-!!! error TS2322:                     Type 'keyof B' is not assignable to type '"valueOf"'.
-!!! error TS2322:                       Type 'string | number | symbol' is not assignable to type '"valueOf"'.
-!!! error TS2322:                         Type 'string' is not assignable to type '"valueOf"'.
+!!! error TS2322:                     Type 'keyof B' is not assignable to type 'number'.
+!!! error TS2322:                       Type 'string | number | symbol' is not assignable to type 'number'.
+!!! error TS2322:                         Type 'string' is not assignable to type 'number'.
         b = a;  // Error
         ~
 !!! error TS2322: Type 'Invariant<A>' is not assignable to type 'Invariant<B>'.
diff --git a/tests/cases/fourslash/completionEntryForUnionProperty2.ts b/tests/cases/fourslash/completionEntryForUnionProperty2.ts
index 1702465aa3ed7..0c5e895439525 100644
--- a/tests/cases/fourslash/completionEntryForUnionProperty2.ts
+++ b/tests/cases/fourslash/completionEntryForUnionProperty2.ts
@@ -3,21 +3,30 @@
 ////interface One {
 ////    commonProperty: string;
 ////    commonFunction(): number;
+////    anotherProperty: Record<string, number>;
 ////}
 ////
 ////interface Two {
 ////    commonProperty: number;
 ////    commonFunction(): number;
+////    anotherProperty: { foo: number }
 ////}
 ////
 ////var x : One | Two;
 ////
-////x.commonProperty./**/
+////x.commonProperty./*1*/;
+////x.anotherProperty./*2*/;
 
 verify.completions({
-    marker: "",
+    marker: "1",
     exact: [
-        { name: "toString", text: "(method) toString(): string (+1 overload)", documentation: "Returns a string representation of a string.", },
+        { name: "toString", text: "(method) toString(): string (+1 overload)", documentation: "Returns a string representation of a string." },
         { name: "valueOf", text: "(method) valueOf(): string | number", documentation: "Returns the primitive value of the specified object." },
+        { name: "toLocaleString", text: "(method) toLocaleString(): string (+1 overload)", documentation: "Returns a date converted to a string using the current locale." },
     ],
 });
+
+verify.completions({
+    marker: '2',
+    includes: { name: 'foo' }
+})