diff --git a/src/routes/index.ts b/src/routes/index.ts
index 263c3ff..d6e5b12 100644
--- a/src/routes/index.ts
+++ b/src/routes/index.ts
@@ -63,7 +63,7 @@ router.get('/SASjsExecutor/do', async (req, res) => {
       .replace(new RegExp('/', 'g'), path.sep)
 
     // If no extension provided, add .sas extension
-    sasCodePath += !sasCodePath.includes('.') ? '.sas' : ''
+    sasCodePath += addExtensionIfNotFound(sasCodePath, 'sas')
 
     await new ExecutionController()
       .execute(sasCodePath, undefined, undefined, { ...req.query })
diff --git a/src/utils/file.ts b/src/utils/file.ts
index cb29f48..c1de713 100644
--- a/src/utils/file.ts
+++ b/src/utils/file.ts
@@ -26,5 +26,11 @@ export const generateUniqueFileName = (fileName: string, extension = '') =>
   ].join('')
 
 export const addExtensionIfNotFound = (value: string, extension: string) => {
-  return !value.includes('.') ? `.${extension}` : ''
+  const valueSplit = value.split('.')
+  
+  if (valueSplit.length < 2) return `.${extension}`
+
+  const hasExt = valueSplit[valueSplit.length - 1].length === 3
+
+  return !hasExt ? `.${extension}` : ''
 }
diff --git a/src/utils/spec/file.spec.ts b/src/utils/spec/file.spec.ts
new file mode 100644
index 0000000..af353e3
--- /dev/null
+++ b/src/utils/spec/file.spec.ts
@@ -0,0 +1,11 @@
+import { addExtensionIfNotFound } from ".."
+
+describe('file utils', () => {
+	it('should add extension if missing', async () => {
+		expect(addExtensionIfNotFound('test', 'ext')).toEqual('.ext')
+		expect(addExtensionIfNotFound('test.test', 'ext')).toEqual('.ext')
+		expect(addExtensionIfNotFound('test.sas', 'ext')).toEqual('')
+		expect(addExtensionIfNotFound('test.test.test', 'ext')).toEqual('.ext')
+		expect(addExtensionIfNotFound('test.test.test.sas', 'ext')).toEqual('')
+	})
+})
\ No newline at end of file