diff --git a/src/config/args.ts b/src/config/args.ts
index 44f1c66..3652b12 100644
--- a/src/config/args.ts
+++ b/src/config/args.ts
@@ -18,8 +18,10 @@ export interface Args {
 
 /**
  * Wrap yargs to exit after completion.
+ *
+ * @TODO: fix it to use argv, not sure if yargs can do that
  */
-export function parseArgs(): Args {
+export function parseArgs(argv: Array<string>) {
   let mode = 'check';
 
   const args = usage(`Usage: salty-dog <mode> [options]`)
@@ -34,10 +36,15 @@ export function parseArgs(): Args {
       command: ['fix'],
       describe: 'validate the source document and insert defaults',
       builder: (yargs: any) => {
-        return yargs.option('coerce', {
-          default: false,
-          type: 'boolean',
-        });
+        return yargs
+          .option('coerce', {
+            default: false,
+            type: 'boolean',
+          })
+          .option('defaults', {
+            default: true,
+            type: 'boolean',
+          });
       },
       handler: (argv: any) => {
         mode = 'fix';
diff --git a/src/index.ts b/src/index.ts
index 7f85bba..4705633 100644
--- a/src/index.ts
+++ b/src/index.ts
@@ -14,7 +14,7 @@ const STATUS_SUCCESS = 0;
 const STATUS_ERROR = 1;
 
 export async function main(argv: Array<string>): Promise<number> {
-  const { args, mode } = parseArgs();
+  const { args, mode } = parseArgs(argv);
   const config = await loadConfig(args[CONFIG_ARGS_NAME], ...args[CONFIG_ARGS_PATH]);
 
   const logger = createLogger(config.data.logger);
@@ -27,18 +27,11 @@ export async function main(argv: Array<string>): Promise<number> {
     return STATUS_ERROR;
   }
 
-  // const schema = new Schema();
-  const result = { errors: [], valid: true }; // schema.match(config);
-  if (!result.valid) {
-    logger.error({ errors: result.errors }, 'config failed to validate');
-    return STATUS_ERROR;
-  }
-
-  const coerce = Reflect.has(args, 'coerce') ? Reflect.get(args, 'coerce') : false;
   const ctx = new VisitorContext({
-    coerce,
-    defaults: mode === 'fix',
+    coerce: args.coerce,
+    defaults: args.defaults,
     logger,
+    mutate: mode === 'fix',
   });
 
   const rules = await loadRules(args.rules, ctx.ajv);
diff --git a/src/rule.ts b/src/rule.ts
index 60cc4d7..85c1377 100644
--- a/src/rule.ts
+++ b/src/rule.ts
@@ -134,7 +134,9 @@ export async function visitRules(ctx: VisitorContext, rules: Array<Rule>, data:
             rule: rule.name,
           }, 'rule passed with modifications');
 
-          applyDiff(item, itemCopy);
+          if (ctx.mutate) {
+            applyDiff(item, itemCopy);
+          }
         } else {
           ctx.logger.info({ rule: rule.name }, 'rule passed');
         }
diff --git a/src/visitor/context.ts b/src/visitor/context.ts
index 2deee38..2242669 100644
--- a/src/visitor/context.ts
+++ b/src/visitor/context.ts
@@ -7,6 +7,7 @@ export interface VisitorContextOptions {
   coerce: boolean;
   defaults: boolean;
   logger: Logger;
+  mutate: boolean;
 }
 
 export class VisitorContext implements VisitorContextOptions, VisitorResult {
@@ -16,6 +17,7 @@ export class VisitorContext implements VisitorContextOptions, VisitorResult {
   public readonly defaults: boolean;
   public readonly errors: Array<any>;
   public readonly logger: Logger;
+  public readonly mutate: boolean;
 
   constructor(options: VisitorContextOptions) {
     this.ajv = new ((Ajv as any).default)({
@@ -27,6 +29,7 @@ export class VisitorContext implements VisitorContextOptions, VisitorResult {
     this.defaults = options.defaults;
     this.errors = [];
     this.logger = options.logger;
+    this.mutate = options.mutate;
   }
 
   public error(options: any, msg: string) {