diff --git a/lib/src/main/java/com/diffplug/spotless/generic/FenceStep.java b/lib/src/main/java/com/diffplug/spotless/generic/FenceStep.java
index 1359053335..7d98219231 100644
--- a/lib/src/main/java/com/diffplug/spotless/generic/FenceStep.java
+++ b/lib/src/main/java/com/diffplug/spotless/generic/FenceStep.java
@@ -103,6 +103,7 @@ private enum Kind {
 	}
 
 	private static class RoundtripAndEqualityState implements Serializable {
+		private static final long serialVersionUID = 272603249547598947L;
 		final String regexPattern;
 		final int regexFlags;
 		final Kind kind;