diff --git a/library/src/commonMain/kotlin/com/chrisjenx/yakcov/TextFieldValueRules.kt b/library/src/commonMain/kotlin/com/chrisjenx/yakcov/TextFieldValueRules.kt
index eb2276d..79cd9a2 100644
--- a/library/src/commonMain/kotlin/com/chrisjenx/yakcov/TextFieldValueRules.kt
+++ b/library/src/commonMain/kotlin/com/chrisjenx/yakcov/TextFieldValueRules.kt
@@ -21,7 +21,7 @@ import yakcov.library.generated.resources.ruleRequired
 import yakcov.library.generated.resources.ruleYear
 
 @Stable
-sealed class TextFieldValueRule {
+abstract class TextFieldValueRule {
     /**
      * Validate the [value] and return an error message if the value is invalid,
      * or null if the value is valid.