diff --git a/src/compiler/commandLineParser.ts b/src/compiler/commandLineParser.ts
index 56767b9420b6b..160debf72e6c3 100644
--- a/src/compiler/commandLineParser.ts
+++ b/src/compiler/commandLineParser.ts
@@ -1013,7 +1013,7 @@ namespace ts {
                                     i++;
                                     break;
                                 case "list":
-                                    const result = parseListTypeOption(<CommandLineOptionOfListType>opt, args[i], errors);
+                                    const result = parseListTypeOption(opt, args[i], errors);
                                     options[opt.name] = result || [];
                                     if (result) {
                                         i++;
@@ -1667,7 +1667,7 @@ namespace ts {
                 return undefined;
             }
             else if (optionDefinition.type === "list") {
-                return getCustomTypeMapOfCommandLineOption((<CommandLineOptionOfListType>optionDefinition).element);
+                return getCustomTypeMapOfCommandLineOption(optionDefinition.element);
             }
             else {
                 return (<CommandLineOptionOfCustomType>optionDefinition).type;
@@ -1731,7 +1731,7 @@ namespace ts {
                 case "object":
                     return {};
                 default:
-                    return (option as CommandLineOptionOfCustomType).type.keys().next().value;
+                    return option.type.keys().next().value;
             }
         }
 
@@ -2338,7 +2338,7 @@ namespace ts {
     function normalizeOptionValue(option: CommandLineOption, basePath: string, value: any): CompilerOptionsValue {
         if (isNullOrUndefined(value)) return undefined;
         if (option.type === "list") {
-            const listOption = <CommandLineOptionOfListType>option;
+            const listOption = option;
             if (listOption.element.isFilePath || !isString(listOption.element.type)) {
                 return <CompilerOptionsValue>filter(map(value, v => normalizeOptionValue(listOption.element, basePath, v)), v => !!v);
             }
@@ -2745,7 +2745,7 @@ namespace ts {
             case "boolean":
                 return typeof value === "boolean" ? value : "";
             case "list":
-                const elementType = (option as CommandLineOptionOfListType).element;
+                const elementType = option.element;
                 return isArray(value) ? value.map(v => getOptionValueWithEmptyStrings(v, elementType)) : "";
             default:
                 return forEachEntry(option.type, (optionEnumValue, optionStringValue) => {
diff --git a/src/harness/harness.ts b/src/harness/harness.ts
index 23ee10d741285..5896ff3a782d7 100644
--- a/src/harness/harness.ts
+++ b/src/harness/harness.ts
@@ -1159,7 +1159,7 @@ namespace Harness {
                 }
                 // If not a primitive, the possible types are specified in what is effectively a map of options.
                 case "list":
-                    return ts.parseListTypeOption(<ts.CommandLineOptionOfListType>option, value, errors);
+                    return ts.parseListTypeOption(option, value, errors);
                 default:
                     return ts.parseCustomTypeOption(<ts.CommandLineOptionOfCustomType>option, value, errors);
             }
diff --git a/src/services/getEditsForFileRename.ts b/src/services/getEditsForFileRename.ts
index a18fab4766fad..5872ade5652b0 100644
--- a/src/services/getEditsForFileRename.ts
+++ b/src/services/getEditsForFileRename.ts
@@ -72,7 +72,7 @@ namespace ts {
                 case "compilerOptions":
                     forEachProperty(property.initializer, (property, propertyName) => {
                         const option = getOptionFromName(propertyName);
-                        if (option && (option.isFilePath || option.type === "list" && (option as CommandLineOptionOfListType).element.isFilePath)) {
+                        if (option && (option.isFilePath || option.type === "list" && option.element.isFilePath)) {
                             updatePaths(property);
                         }
                         else if (propertyName === "paths") {