diff --git a/guava-gwt/src-super/com/google/common/collect/super/com/google/common/collect/RegularImmutableBiMap.java b/guava-gwt/src-super/com/google/common/collect/super/com/google/common/collect/RegularImmutableBiMap.java
index 0afe66004da9..0dfb2fc63d86 100644
--- a/guava-gwt/src-super/com/google/common/collect/super/com/google/common/collect/RegularImmutableBiMap.java
+++ b/guava-gwt/src-super/com/google/common/collect/super/com/google/common/collect/RegularImmutableBiMap.java
@@ -29,7 +29,7 @@ final class RegularImmutableBiMap<K, V> extends ImmutableBiMap<K, V> {
   static final RegularImmutableBiMap<Object, Object> EMPTY =
       new RegularImmutableBiMap<Object, Object>();
 
-  private final ImmutableBiMap<V, K> inverse;
+  private final transient ImmutableBiMap<V, K> inverse;
 
   @SuppressWarnings("unchecked") // used only for the empty map, which works for any types
   RegularImmutableBiMap() {