diff --git a/error-prone-contrib/src/main/java/tech/picnic/errorprone/refastertemplates/RxJavaFlowableToReactorTemplates.java b/error-prone-contrib/src/main/java/tech/picnic/errorprone/refastertemplates/RxJavaFlowableToReactorTemplates.java
index 61dd078d..9ce0a20c 100644
--- a/error-prone-contrib/src/main/java/tech/picnic/errorprone/refastertemplates/RxJavaFlowableToReactorTemplates.java
+++ b/error-prone-contrib/src/main/java/tech/picnic/errorprone/refastertemplates/RxJavaFlowableToReactorTemplates.java
@@ -681,7 +681,7 @@ final class RxJavaFlowableToReactorTemplates {
 
     @AfterTemplate
     Single<T> after(Flowable<T> flowable) {
-      return RxJava2Adapter.monoToSingle(RxJava2Adapter.flowableToFlux(flowable).next());
+      return RxJava2Adapter.monoToSingle(RxJava2Adapter.flowableToFlux(flowable).next().single());
     }
   }
 
diff --git a/error-prone-contrib/src/main/java/tech/picnic/errorprone/refastertemplates/RxJavaSingleToReactorTemplates.java b/error-prone-contrib/src/main/java/tech/picnic/errorprone/refastertemplates/RxJavaSingleToReactorTemplates.java
index b3adafbb..88ba6a26 100644
--- a/error-prone-contrib/src/main/java/tech/picnic/errorprone/refastertemplates/RxJavaSingleToReactorTemplates.java
+++ b/error-prone-contrib/src/main/java/tech/picnic/errorprone/refastertemplates/RxJavaSingleToReactorTemplates.java
@@ -280,7 +280,7 @@ final class RxJavaSingleToReactorTemplates {
     }
   }
 
-  // XXX: Test this one.
+  // XXX: Write a test.
   abstract static class SingleFlatMapUnwrapLambda<T, R> {
     @Placeholder
     abstract Mono<? extends R> placeholder(@MayOptionallyUse T input);
@@ -530,7 +530,12 @@ final class RxJavaSingleToReactorTemplates {
                   e ->
                       RxJava2Adapter.singleToMono(
                           Single.wrap(
-                              RxJavaReactorMigrationUtil.toJdkFunction(function).apply(e)))));
+                              RxJavaReactorMigrationUtil.toJdkFunction(
+                                      (Function<
+                                              ? super Throwable,
+                                              ? extends SingleSource<? extends T>>)
+                                          function)
+                                  .apply(e)))));
     }
   }
 
diff --git a/error-prone-contrib/src/main/java/tech/picnic/errorprone/refastertemplates/RxJavaToReactorTemplates.java b/error-prone-contrib/src/main/java/tech/picnic/errorprone/refastertemplates/RxJavaToReactorTemplates.java
index 87240fa0..a1aa5a63 100644
--- a/error-prone-contrib/src/main/java/tech/picnic/errorprone/refastertemplates/RxJavaToReactorTemplates.java
+++ b/error-prone-contrib/src/main/java/tech/picnic/errorprone/refastertemplates/RxJavaToReactorTemplates.java
@@ -207,17 +207,17 @@ public final class RxJavaToReactorTemplates {
   @SuppressWarnings("NoFunctionalReturnType")
   static final class UnnecessaryConsumerConversion<T> {
     @BeforeTemplate
-    java.util.function.Consumer<T> before(@CanTransformToTargetType Consumer<T> consumer) {
+    java.util.function.Consumer<? extends T> before(@CanTransformToTargetType Consumer<? extends T> consumer) {
       return RxJavaReactorMigrationUtil.toJdkConsumer(consumer);
     }
 
     @AfterTemplate
-    java.util.function.Consumer<T> after(java.util.function.Consumer<T> consumer) {
+    java.util.function.Consumer<? extends T> after(java.util.function.Consumer<? extends T> consumer) {
       return consumer;
     }
   }
 
-  static final class UnnecessaryRunnableConversion<T> {
+  static final class UnnecessaryRunnableConversion {
     @BeforeTemplate
     Runnable before(@CanTransformToTargetType Action action) {
       return RxJavaReactorMigrationUtil.toRunnable(action);
@@ -229,16 +229,15 @@ public final class RxJavaToReactorTemplates {
     }
   }
 
-  // XXX: This one is without CanBeTransformedTo...
   @SuppressWarnings("NoFunctionalReturnType")
   static final class UnnecessaryPredicateConversion<T> {
     @BeforeTemplate
-    java.util.function.Predicate<T> before(Predicate<T> predicate) {
+    java.util.function.Predicate<? extends T> before(@CanTransformToTargetType Predicate<? extends T> predicate) {
       return RxJavaReactorMigrationUtil.toJdkPredicate(predicate);
     }
 
     @AfterTemplate
-    java.util.function.Predicate<T> after(java.util.function.Predicate<T> predicate) {
+    java.util.function.Predicate<? extends T> after(java.util.function.Predicate<? extends T> predicate) {
       return predicate;
     }
   }
diff --git a/error-prone-contrib/src/test/resources/tech/picnic/errorprone/bugpatterns/RxJavaFlowableToReactorTemplatesTestOutput.java b/error-prone-contrib/src/test/resources/tech/picnic/errorprone/bugpatterns/RxJavaFlowableToReactorTemplatesTestOutput.java
index 30ec39c0..1fbca861 100644
--- a/error-prone-contrib/src/test/resources/tech/picnic/errorprone/bugpatterns/RxJavaFlowableToReactorTemplatesTestOutput.java
+++ b/error-prone-contrib/src/test/resources/tech/picnic/errorprone/bugpatterns/RxJavaFlowableToReactorTemplatesTestOutput.java
@@ -96,7 +96,7 @@ final class RxJavaFlowableToReactorTemplatesTest implements RefasterTemplateTest
   }
 
   Single<Integer> testFlowableFirstOrError() {
-    return RxJava2Adapter.monoToSingle(RxJava2Adapter.flowableToFlux(Flowable.just(1)).next());
+    return RxJava2Adapter.monoToSingle(RxJava2Adapter.flowableToFlux(Flowable.just(1)).next().single());
   }
 
   Completable testFlowableFlatMapCompletable() {