diff --git a/webgoat-container/src/main/java/org/owasp/webgoat/users/UserForm.java b/webgoat-container/src/main/java/org/owasp/webgoat/users/UserForm.java
index e2062cbdd..1e0c44000 100644
--- a/webgoat-container/src/main/java/org/owasp/webgoat/users/UserForm.java
+++ b/webgoat-container/src/main/java/org/owasp/webgoat/users/UserForm.java
@@ -17,7 +17,7 @@ public class UserForm {
 
     @NotNull
     @Size(min=6, max=20)
-    @Pattern(regexp = "[a-zA-Z0-9-]*", message = "can only contain letters, digits, and -")
+    @Pattern(regexp = "[a-z0-9-]*", message = "can only contain lowercase letters, digits, and -")
     private String username;
     @NotNull
     @Size(min=6, max=10)