diff --git a/src/composables/useDemoAccountGenerator.ts b/src/composables/useDemoAccountGenerator.ts
index d0689da..4450988 100644
--- a/src/composables/useDemoAccountGenerator.ts
+++ b/src/composables/useDemoAccountGenerator.ts
@@ -22,16 +22,29 @@ export function useDemoAccountGenerator() {
     return password
   }
 
+  // Generate unique username < 20 characters long
+  function generateUsername() {
+    const maxLength = 20;
+    const numberDictionary = NumberDictionary.generate({ min: 100, max: 999 });
+
+    while (true) {
+      const username = uniqueNamesGenerator({
+        dictionaries: [adjectives, animals, numberDictionary],
+        separator: '',
+        length: 3,
+        style: 'capital'
+      });
+
+      if (username.length <= maxLength) {
+        return username;
+      }
+      // otherwise reroll
+    }
+  }
+
   // Generate unique username and random password
   function generateCredentials(): GeneratedCredentials {
-    // Use only 2 dictionaries to keep username shorter
-    const numberDictionary = NumberDictionary.generate({ min: 100, max: 999 });
-    const username = uniqueNamesGenerator({
-      dictionaries: [adjectives, animals, numberDictionary],
-      separator: '',
-      length: 3,
-      style: 'capital'
-    })
+    const username = generateUsername()
 
     const password = generateRandomPassword()
     const email = `${username}@demo.local`