diff --git a/packages/babel-parser/src/plugins/typescript/index.js b/packages/babel-parser/src/plugins/typescript/index.js
index 827e43a7499e..4d708dbba095 100644
--- a/packages/babel-parser/src/plugins/typescript/index.js
+++ b/packages/babel-parser/src/plugins/typescript/index.js
@@ -2427,10 +2427,7 @@ export default (superClass: Class<Parser>): Class<Parser> =>
     toAssignableList(
       exprList: N.Expression[],
       isBinding: ?boolean,
-      contextDescription: string,
     ): $ReadOnlyArray<N.Pattern> {
-      const isAssignmentExpression =
-        contextDescription === "assignment expression";
       for (let i = 0; i < exprList.length; i++) {
         const expr = exprList[i];
         if (!expr) continue;
@@ -2440,7 +2437,7 @@ export default (superClass: Class<Parser>): Class<Parser> =>
             break;
           case "TSAsExpression":
           case "TSTypeAssertion":
-            if (isAssignmentExpression) {
+            if (!isBinding) {
               exprList[i] = this.typeCastToParameter(expr);
             } else {
               this.raise(