diff --git a/README.md b/README.md
index 1d5c23a..d35e7a1 100644
--- a/README.md
+++ b/README.md
@@ -48,7 +48,9 @@ npm install -g dts-bundle-generator
 ## Usage
 
 ```
-usage: dts-bundle-generator [-h] -o OUTFILE [-v] [--no-check] [--output-source-file] file
+usage: dts-bundle-generator [-h] -o OUTFILE [-v] [--no-check] [--output-source-file]
+              [--fail-on-class]
+              file
 
 Positional arguments:
   file
@@ -60,6 +62,7 @@ Optional arguments:
   -v, --verbose         Enable verbose logging
   --no-check            Skip validation of generated d.ts file
   --output-source-file  Add comment with file path the definitions came from
+  --fail-on-class       Fail if generated dts contains class declaration
 ```
 
 Example:
diff --git a/src/bundle-generator.ts b/src/bundle-generator.ts
index 86b1158..6680aff 100644
--- a/src/bundle-generator.ts
+++ b/src/bundle-generator.ts
@@ -6,6 +6,7 @@ import { verboseLog, normalLog } from './logger';
 
 export interface GenerationOptions {
 	outputFilenames?: boolean;
+	failOnClass?: boolean;
 }
 
 const skippedNodes = [
@@ -66,6 +67,13 @@ export function generateDtsBundle(filePath: string, options: GenerationOptions =
 			const hasNodeExportKeyword = hasNodeModifier(node, ts.SyntaxKind.ExportKeyword);
 
 			if (node.kind === ts.SyntaxKind.ClassDeclaration || node.kind === ts.SyntaxKind.EnumDeclaration) {
+				if (options.failOnClass === true && node.kind === ts.SyntaxKind.ClassDeclaration) {
+					const classDecl = (node as ts.ClassDeclaration);
+					const className = classDecl.name ? classDecl.name.text : '';
+					const errorMessage = `Class was found in generated dts.\n ${className} from ${sourceFile.fileName}`;
+					throw new Error(errorMessage);
+				}
+
 				// not all classes and enums can be exported - only exported from root file
 				let shouldNodeHasExportKeyword = isDeclarationExported(rootFileExports, typeChecker, node as (ts.ClassDeclaration | ts.EnumDeclaration));
 				if (node.kind === ts.SyntaxKind.EnumDeclaration) {
diff --git a/src/cli.ts b/src/cli.ts
index 1ef6c14..bc39a34 100644
--- a/src/cli.ts
+++ b/src/cli.ts
@@ -49,6 +49,17 @@ parser.addArgument(
 	},
 );
 
+parser.addArgument(
+	['--fail-on-class'],
+	{
+		action: 'storeTrue',
+		defaultValue: false,
+		dest: 'failOnClass',
+		help: 'Fail if generated dts contains class declaration',
+		type: Boolean,
+	},
+);
+
 parser.addArgument(['file'], { nargs: 1 });
 
 const args = parser.parseArgs();
@@ -58,7 +69,11 @@ if (args.verbose) {
 
 try {
 	const fileName = args.file[0];
-	const generatedDts = generateDtsBundle(fileName, { outputFilenames: args.outputSourceFileName });
+	const generatedDts = generateDtsBundle(fileName, {
+		failOnClass: args.failOnClass,
+		outputFilenames: args.outputSourceFileName,
+	});
+
 	normalLog(`Writing generated file to ${args.outFile}...`);
 	fs.writeFileSync(args.outFile, generatedDts);