diff --git a/src/compiler/commandLineParser.ts b/src/compiler/commandLineParser.ts
index c56a18b3ab2..9b7558f315a 100644
--- a/src/compiler/commandLineParser.ts
+++ b/src/compiler/commandLineParser.ts
@@ -243,8 +243,9 @@ namespace ts {
                 "node": ModuleResolutionKind.NodeJs,
                 "classic": ModuleResolutionKind.Classic
             },
-            description: Diagnostics.Specifies_module_resolution_strategy_Colon_node_Node_or_classic_TypeScript_pre_1_6
-        }        
+            description: Diagnostics.Specifies_module_resolution_strategy_Colon_node_Node_js_or_classic_TypeScript_pre_1_6,
+            error: Diagnostics.Argument_for_moduleResolution_option_must_be_node_or_classic,
+        }
     ];
 
     /* @internal */
@@ -327,7 +328,7 @@ namespace ts {
                                     options[opt.name] = map[key];
                                 }
                                 else {
-                                    errors.push(createCompilerDiagnostic(opt.error));
+                                    errors.push(createCompilerDiagnostic((<CommandLineOptionOfCustomType>opt).error));
                                 }
                         }
                     }
@@ -440,7 +441,7 @@ namespace ts {
                                     value = optType[key];
                                 }
                                 else {
-                                    errors.push(createCompilerDiagnostic(opt.error));
+                                    errors.push(createCompilerDiagnostic((<CommandLineOptionOfCustomType>opt).error));
                                     value = 0;
                                 }
                             }
diff --git a/src/compiler/diagnosticInformationMap.generated.ts b/src/compiler/diagnosticInformationMap.generated.ts
index f7351bf6912..1c9232d1515 100644
--- a/src/compiler/diagnosticInformationMap.generated.ts
+++ b/src/compiler/diagnosticInformationMap.generated.ts
@@ -560,13 +560,14 @@ namespace ts {
         Specifies_the_end_of_line_sequence_to_be_used_when_emitting_files_Colon_CRLF_dos_or_LF_unix: { code: 6060, category: DiagnosticCategory.Message, key: "Specifies the end of line sequence to be used when emitting files: 'CRLF' (dos) or 'LF' (unix)." },
         NEWLINE: { code: 6061, category: DiagnosticCategory.Message, key: "NEWLINE" },
         Argument_for_newLine_option_must_be_CRLF_or_LF: { code: 6062, category: DiagnosticCategory.Error, key: "Argument for '--newLine' option must be 'CRLF' or 'LF'." },
+        Argument_for_moduleResolution_option_must_be_node_or_classic: { code: 6063, category: DiagnosticCategory.Error, key: "Argument for '--moduleResolution' option must be 'node' or 'classic'." },
         Specify_JSX_code_generation_Colon_preserve_or_react: { code: 6080, category: DiagnosticCategory.Message, key: "Specify JSX code generation: 'preserve' or 'react'" },
         Argument_for_jsx_must_be_preserve_or_react: { code: 6081, category: DiagnosticCategory.Message, key: "Argument for '--jsx' must be 'preserve' or 'react'." },
         Enables_experimental_support_for_ES7_decorators: { code: 6065, category: DiagnosticCategory.Message, key: "Enables experimental support for ES7 decorators." },
         Enables_experimental_support_for_emitting_type_metadata_for_decorators: { code: 6066, category: DiagnosticCategory.Message, key: "Enables experimental support for emitting type metadata for decorators." },
         Option_experimentalAsyncFunctions_cannot_be_specified_when_targeting_ES5_or_lower: { code: 6067, category: DiagnosticCategory.Message, key: "Option 'experimentalAsyncFunctions' cannot be specified when targeting ES5 or lower." },
         Enables_experimental_support_for_ES7_async_functions: { code: 6068, category: DiagnosticCategory.Message, key: "Enables experimental support for ES7 async functions." },
-        Specifies_module_resolution_strategy_Colon_node_Node_or_classic_TypeScript_pre_1_6: { code: 6069, category: DiagnosticCategory.Message, key: "Specifies module resolution strategy: 'node' (Node) or 'classic' (TypeScript pre 1.6) ." },
+        Specifies_module_resolution_strategy_Colon_node_Node_js_or_classic_TypeScript_pre_1_6: { code: 6069, category: DiagnosticCategory.Message, key: "Specifies module resolution strategy: 'node' (Node.js) or 'classic' (TypeScript pre-1.6)." },
         Initializes_a_TypeScript_project_and_creates_a_tsconfig_json_file: { code: 6070, category: DiagnosticCategory.Message, key: "Initializes a TypeScript project and creates a tsconfig.json file." },
         Successfully_created_a_tsconfig_json_file: { code: 6071, category: DiagnosticCategory.Message, key: "Successfully created a tsconfig.json file." },
         Suppress_excess_property_checks_for_object_literals: { code: 6072, category: DiagnosticCategory.Message, key: "Suppress excess property checks for object literals." },
diff --git a/src/compiler/diagnosticMessages.json b/src/compiler/diagnosticMessages.json
index 9fd08ef9bca..f6875c45c47 100644
--- a/src/compiler/diagnosticMessages.json
+++ b/src/compiler/diagnosticMessages.json
@@ -2230,6 +2230,11 @@
         "category": "Error",
         "code": 6062
     },
+    "Argument for '--moduleResolution' option must be 'node' or 'classic'.": {
+        "category": "Error",
+        "code": 6063
+    },
+
     "Specify JSX code generation: 'preserve' or 'react'": {
         "category": "Message",
         "code": 6080
@@ -2254,7 +2259,7 @@
         "category": "Message",
         "code": 6068
     },
-    "Specifies module resolution strategy: 'node' (Node) or 'classic' (TypeScript pre 1.6) .": {
+    "Specifies module resolution strategy: 'node' (Node.js) or 'classic' (TypeScript pre-1.6).": {
         "category": "Message",
         "code": 6069
     },
diff --git a/src/compiler/types.ts b/src/compiler/types.ts
index 47182e39527..f9d1b506274 100644
--- a/src/compiler/types.ts
+++ b/src/compiler/types.ts
@@ -2112,17 +2112,30 @@ namespace ts {
     }
 
     /* @internal */
-    export interface CommandLineOption {
+    interface CommandLineOptionBase {
         name: string;
         type: string | Map<number>;         // "string", "number", "boolean", or an object literal mapping named values to actual values
         isFilePath?: boolean;               // True if option value is a path or fileName
         shortName?: string;                 // A short mnemonic for convenience - for instance, 'h' can be used in place of 'help'
         description?: DiagnosticMessage;    // The message describing what the command line switch does
         paramType?: DiagnosticMessage;      // The name to be used for a non-boolean option's parameter
-        error?: DiagnosticMessage;          // The error given when the argument does not fit a customized 'type'
         experimental?: boolean;
     }
 
+    /* @internal */
+    export interface CommandLineOptionOfPrimitiveType extends CommandLineOptionBase {
+        type: string;                   // "string" | "number" | "boolean"
+    }
+
+    /* @internal */
+    export interface CommandLineOptionOfCustomType extends CommandLineOptionBase {
+        type: Map<number>;             // an object literal mapping named values to actual values
+        error: DiagnosticMessage;      // The error given when the argument does not fit a customized 'type'
+    }
+
+    /* @internal */
+    export type CommandLineOption = CommandLineOptionOfCustomType | CommandLineOptionOfPrimitiveType;
+
     /* @internal */
     export const enum CharacterCodes {
         nullCharacter = 0,