diff --git a/action.yml b/action.yml
index 04d4c4a..38ed43a 100644
--- a/action.yml
+++ b/action.yml
@@ -10,7 +10,7 @@ inputs:
     required: true
 
   type:
-    description: "Configure orientation for devcard"
+    description: 'Configure orientation for devcard. Must be either "default" or "wide"'
     default: default
     required: false
 
diff --git a/src/index.ts b/src/index.ts
index ed4560e..45e1f98 100644
--- a/src/index.ts
+++ b/src/index.ts
@@ -33,6 +33,11 @@ const devcardURL = (user_id: string, type = 'default'): string =>
 			throw new Error('Filename is required')
 		}
 
+		// throw an error if type is invalid, must be either "default" or "wide"
+		if (type && !['default', 'wide'].includes(type)) {
+			throw new Error('Invalid type. Must be either "default" or "wide"')
+		}
+
 		console.log(`Dryrun`, dryrun)
 
 		// Fetch the latest devcard