diff --git a/src/compiler/tsc.ts b/src/compiler/tsc.ts
index 10d4a0c1d3679..a7304eebe4b81 100644
--- a/src/compiler/tsc.ts
+++ b/src/compiler/tsc.ts
@@ -43,66 +43,6 @@ namespace ts {
         }
     }
 
-    /**
-     * Checks to see if the locale is in the appropriate format,
-     * and if it is, attempts to set the appropriate language.
-     */
-    function validateLocaleAndSetLanguage(locale: string, errors: Diagnostic[]): boolean {
-        const matchResult = /^([a-z]+)([_\-]([a-z]+))?$/.exec(locale.toLowerCase());
-
-        if (!matchResult) {
-            errors.push(createCompilerDiagnostic(Diagnostics.Locale_must_be_of_the_form_language_or_language_territory_For_example_0_or_1, "en", "ja-jp"));
-            return false;
-        }
-
-        const language = matchResult[1];
-        const territory = matchResult[3];
-
-        // First try the entire locale, then fall back to just language if that's all we have.
-        // Either ways do not fail, and fallback to the English diagnostic strings.
-        if (!trySetLanguageAndTerritory(language, territory, errors)) {
-            trySetLanguageAndTerritory(language, undefined, errors);
-        }
-
-        return true;
-    }
-
-    function trySetLanguageAndTerritory(language: string, territory: string, errors: Diagnostic[]): boolean {
-        const compilerFilePath = normalizePath(sys.getExecutingFilePath());
-        const containingDirectoryPath = getDirectoryPath(compilerFilePath);
-
-        let filePath = combinePaths(containingDirectoryPath, language);
-
-        if (territory) {
-            filePath = filePath + "-" + territory;
-        }
-
-        filePath = sys.resolvePath(combinePaths(filePath, "diagnosticMessages.generated.json"));
-
-        if (!sys.fileExists(filePath)) {
-            return false;
-        }
-
-        // TODO: Add codePage support for readFile?
-        let fileContents = "";
-        try {
-            fileContents = sys.readFile(filePath);
-        }
-        catch (e) {
-            errors.push(createCompilerDiagnostic(Diagnostics.Unable_to_open_file_0, filePath));
-            return false;
-        }
-        try {
-            ts.localizedDiagnosticMessages = JSON.parse(fileContents);
-        }
-        catch (e) {
-            errors.push(createCompilerDiagnostic(Diagnostics.Corrupted_locale_file_0, filePath));
-            return false;
-        }
-
-        return true;
-    }
-
     function countLines(program: Program): number {
         let count = 0;
         forEach(program.getSourceFiles(), file => {
@@ -263,7 +203,7 @@ namespace ts {
                 reportDiagnostic(createCompilerDiagnostic(Diagnostics.The_current_host_does_not_support_the_0_option, "--locale"), /* host */ undefined);
                 return sys.exit(ExitStatus.DiagnosticsPresent_OutputsSkipped);
             }
-            validateLocaleAndSetLanguage(commandLine.options.locale, commandLine.errors);
+            validateLocaleAndSetLanguage(commandLine.options.locale, sys, commandLine.errors);
         }
 
         // If there are any errors due to command line parsing and/or
diff --git a/src/compiler/utilities.ts b/src/compiler/utilities.ts
index 546416884f1dc..09318fbe41ddd 100644
--- a/src/compiler/utilities.ts
+++ b/src/compiler/utilities.ts
@@ -472,15 +472,15 @@ namespace ts {
 
     export function getTextOfPropertyName(name: PropertyName): string {
         switch (name.kind) {
-        case SyntaxKind.Identifier:
-            return (<Identifier>name).text;
-        case SyntaxKind.StringLiteral:
-        case SyntaxKind.NumericLiteral:
-            return (<LiteralExpression>name).text;
-        case SyntaxKind.ComputedPropertyName:
-            if (isStringOrNumericLiteral((<ComputedPropertyName>name).expression)) {
-                return (<LiteralExpression>(<ComputedPropertyName>name).expression).text;
-            }
+            case SyntaxKind.Identifier:
+                return (<Identifier>name).text;
+            case SyntaxKind.StringLiteral:
+            case SyntaxKind.NumericLiteral:
+                return (<LiteralExpression>name).text;
+            case SyntaxKind.ComputedPropertyName:
+                if (isStringOrNumericLiteral((<ComputedPropertyName>name).expression)) {
+                    return (<LiteralExpression>(<ComputedPropertyName>name).expression).text;
+                }
         }
 
         return undefined;
@@ -4554,4 +4554,71 @@ namespace ts {
 
         return flags;
     }
+
+    /**
+      * Checks to see if the locale is in the appropriate format,
+      * and if it is, attempts to set the appropriate language.
+      */
+    export function validateLocaleAndSetLanguage(
+        locale: string,
+        sys: { getExecutingFilePath(): string, resolvePath(path: string): string, fileExists(fileName: string): boolean, readFile(fileName: string): string },
+        errors?: Diagnostic[]) {
+        const matchResult = /^([a-z]+)([_\-]([a-z]+))?$/.exec(locale.toLowerCase());
+
+        if (!matchResult) {
+            if (errors) {
+                errors.push(createCompilerDiagnostic(Diagnostics.Locale_must_be_of_the_form_language_or_language_territory_For_example_0_or_1, "en", "ja-jp"));
+            }
+            return;
+        }
+
+        const language = matchResult[1];
+        const territory = matchResult[3];
+
+        // First try the entire locale, then fall back to just language if that's all we have.
+        // Either ways do not fail, and fallback to the English diagnostic strings.
+        if (!trySetLanguageAndTerritory(language, territory, errors)) {
+            trySetLanguageAndTerritory(language, /*territory*/ undefined, errors);
+        }
+
+        function trySetLanguageAndTerritory(language: string, territory: string, errors?: Diagnostic[]): boolean {
+            const compilerFilePath = normalizePath(sys.getExecutingFilePath());
+            const containingDirectoryPath = getDirectoryPath(compilerFilePath);
+
+            let filePath = combinePaths(containingDirectoryPath, language);
+
+            if (territory) {
+                filePath = filePath + "-" + territory;
+            }
+
+            filePath = sys.resolvePath(combinePaths(filePath, "diagnosticMessages.generated.json"));
+
+            if (!sys.fileExists(filePath)) {
+                return false;
+            }
+
+            // TODO: Add codePage support for readFile?
+            let fileContents = "";
+            try {
+                fileContents = sys.readFile(filePath);
+            }
+            catch (e) {
+                if (errors) {
+                    errors.push(createCompilerDiagnostic(Diagnostics.Unable_to_open_file_0, filePath));
+                }
+                return false;
+            }
+            try {
+                ts.localizedDiagnosticMessages = JSON.parse(fileContents);
+            }
+            catch (e) {
+                if (errors) {
+                    errors.push(createCompilerDiagnostic(Diagnostics.Corrupted_locale_file_0, filePath));
+                }
+                return false;
+            }
+
+            return true;
+        }
+    }
 }
diff --git a/src/server/server.ts b/src/server/server.ts
index 220b0d90c65e6..081673958d6ce 100644
--- a/src/server/server.ts
+++ b/src/server/server.ts
@@ -577,6 +577,11 @@ namespace ts.server {
         }
     }
 
+    const localeStr = findArgument("--locale");
+    if (localeStr) {
+        validateLocaleAndSetLanguage(localeStr, sys);
+    }
+
     const useSingleInferredProject = hasArgument("--useSingleInferredProject");
     const disableAutomaticTypingAcquisition = hasArgument("--disableAutomaticTypingAcquisition");
     const telemetryEnabled = hasArgument(Arguments.EnableTelemetry);