diff --git a/error-prone-contrib/src/main/java/tech/picnic/errorprone/refasterrules/ReactorRules.java b/error-prone-contrib/src/main/java/tech/picnic/errorprone/refasterrules/ReactorRules.java
index 6ed728f2c5..c78dc4991e 100644
--- a/error-prone-contrib/src/main/java/tech/picnic/errorprone/refasterrules/ReactorRules.java
+++ b/error-prone-contrib/src/main/java/tech/picnic/errorprone/refasterrules/ReactorRules.java
@@ -939,7 +939,11 @@ Flux<T> after(Mono<T> mono) {
   static final class MonoThen<T> {
     @BeforeTemplate
     Mono<@Nullable Void> before(Mono<T> mono) {
-      return Refaster.anyOf(mono.ignoreElement().then(), mono.flux().then());
+      return Refaster.anyOf(
+          mono.ignoreElement().then(),
+          mono.flux().then(),
+          Mono.when(mono),
+          Mono.whenDelayError(mono));
     }
 
     @AfterTemplate
diff --git a/error-prone-contrib/src/test/resources/tech/picnic/errorprone/refasterrules/ReactorRulesTestInput.java b/error-prone-contrib/src/test/resources/tech/picnic/errorprone/refasterrules/ReactorRulesTestInput.java
index 1129f1c5c1..50c19815b0 100644
--- a/error-prone-contrib/src/test/resources/tech/picnic/errorprone/refasterrules/ReactorRulesTestInput.java
+++ b/error-prone-contrib/src/test/resources/tech/picnic/errorprone/refasterrules/ReactorRulesTestInput.java
@@ -342,7 +342,11 @@ ImmutableSet<Flux<String>> testMonoFlux() {
   }
 
   ImmutableSet<Mono<Void>> testMonoThen() {
-    return ImmutableSet.of(Mono.just("foo").ignoreElement().then(), Mono.just("bar").flux().then());
+    return ImmutableSet.of(
+        Mono.just("foo").ignoreElement().then(),
+        Mono.just("bar").flux().then(),
+        Mono.when(Mono.just("baz")),
+        Mono.whenDelayError(Mono.just("qux")));
   }
 
   ImmutableSet<Mono<Void>> testFluxThen() {
diff --git a/error-prone-contrib/src/test/resources/tech/picnic/errorprone/refasterrules/ReactorRulesTestOutput.java b/error-prone-contrib/src/test/resources/tech/picnic/errorprone/refasterrules/ReactorRulesTestOutput.java
index b8739b6443..6e552378da 100644
--- a/error-prone-contrib/src/test/resources/tech/picnic/errorprone/refasterrules/ReactorRulesTestOutput.java
+++ b/error-prone-contrib/src/test/resources/tech/picnic/errorprone/refasterrules/ReactorRulesTestOutput.java
@@ -340,7 +340,11 @@ ImmutableSet<Flux<String>> testMonoFlux() {
   }
 
   ImmutableSet<Mono<Void>> testMonoThen() {
-    return ImmutableSet.of(Mono.just("foo").then(), Mono.just("bar").then());
+    return ImmutableSet.of(
+        Mono.just("foo").then(),
+        Mono.just("bar").then(),
+        Mono.just("baz").then(),
+        Mono.just("qux").then());
   }
 
   ImmutableSet<Mono<Void>> testFluxThen() {