diff --git a/error-prone-contrib/src/main/java/tech/picnic/errorprone/bugpatterns/NonEmptyMono.java b/error-prone-contrib/src/main/java/tech/picnic/errorprone/bugpatterns/NonEmptyMono.java
index a6ae88cd542..37f530be56a 100644
--- a/error-prone-contrib/src/main/java/tech/picnic/errorprone/bugpatterns/NonEmptyMono.java
+++ b/error-prone-contrib/src/main/java/tech/picnic/errorprone/bugpatterns/NonEmptyMono.java
@@ -17,6 +17,7 @@
 import com.google.errorprone.util.ASTHelpers;
 import com.sun.source.tree.ExpressionTree;
 import com.sun.source.tree.MethodInvocationTree;
+import java.util.function.BiFunction;
 import reactor.core.publisher.Mono;
 import tech.picnic.errorprone.bugpatterns.util.SourceCode;
 
@@ -62,6 +63,10 @@ public final class NonEmptyMono extends BugChecker implements MethodInvocationTr
                   "last",
                   "reduceWith",
                   "single"),
+          instanceMethod()
+              .onDescendantOf("reactor.core.publisher.Flux")
+              .named("reduce")
+              .withParameters(Object.class.getName(), BiFunction.class.getName()),
           instanceMethod()
               .onDescendantOf("reactor.core.publisher.Mono")
               .namedAnyOf("defaultIfEmpty", "hasElement", "single"));
diff --git a/error-prone-contrib/src/test/java/tech/picnic/errorprone/bugpatterns/NonEmptyMonoTest.java b/error-prone-contrib/src/test/java/tech/picnic/errorprone/bugpatterns/NonEmptyMonoTest.java
index 820ed28a2ff..09b95549dee 100644
--- a/error-prone-contrib/src/test/java/tech/picnic/errorprone/bugpatterns/NonEmptyMonoTest.java
+++ b/error-prone-contrib/src/test/java/tech/picnic/errorprone/bugpatterns/NonEmptyMonoTest.java
@@ -28,37 +28,48 @@ void identification() {
             "class A {",
             "  void m() {",
             "    // BUG: Diagnostic contains:",
-            "    Flux.just().all(x -> true).defaultIfEmpty(true);",
+            "    Flux.just(1).all(x -> true).defaultIfEmpty(true);",
             "    // BUG: Diagnostic contains:",
-            "    Flux.just().any(x -> true).single();",
+            "    Flux.just(1).any(x -> true).single();",
             "",
             "    // BUG: Diagnostic contains:",
-            "    Flux.just().collect(toImmutableList()).switchIfEmpty(Mono.just(ImmutableList.of()));",
+            "    Flux.just(1).collect(toImmutableList()).switchIfEmpty(Mono.just(ImmutableList.of()));",
             "    // BUG: Diagnostic contains:",
-            "    Flux.just().collectList().defaultIfEmpty(ImmutableList.of());",
+            "    Flux.just(1).collectList().defaultIfEmpty(ImmutableList.of());",
             "    // BUG: Diagnostic contains:",
-            "    Flux.just().collectMap(identity()).single();",
-            "    Flux.just()",
+            "    Flux.just(1).collectMap(identity()).single();",
+            "    Flux.just(1)",
             "        .collectMultimap(identity(), identity(), ImmutableMap::of)",
             "        // BUG: Diagnostic contains:",
             "        .switchIfEmpty(Mono.just(ImmutableMap.of()));",
             "    // BUG: Diagnostic contains:",
-            "    Flux.just().collectSortedList((o1, o2) -> 1).defaultIfEmpty(ImmutableList.of());",
+            "    Flux.just(1).collectSortedList((o1, o2) -> 1).defaultIfEmpty(ImmutableList.of());",
             "",
             "    // BUG: Diagnostic contains:",
-            "    Flux.just().count().single();",
+            "    Flux.just(1).count().single();",
+            "    // BUG: Diagnostic contains:",
+            "    Flux.just(1).elementAt(0).defaultIfEmpty(1);",
+            "    // BUG: Diagnostic contains:",
+            "    Flux.just(1).hasElement(0).single();",
+            "    // BUG: Diagnostic contains:",
+            "    Flux.just(1).hasElements().switchIfEmpty(Mono.just(true));",
             "    // BUG: Diagnostic contains:",
-            "    Flux.just().elementAt(0).defaultIfEmpty(1);",
+            "    Flux.just(1).last().defaultIfEmpty(1);",
             "    // BUG: Diagnostic contains:",
-            "    Flux.just().hasElement(0).single();",
+            "    Flux.just(1).reduceWith(() -> 1, (x, y) -> x).single();",
             "    // BUG: Diagnostic contains:",
-            "    Flux.just().hasElements().switchIfEmpty(Mono.just(true));",
+            "    Flux.just(1).single().switchIfEmpty(Mono.just(1));",
+            "",
+            "    Flux.just(1).reduce(Integer::sum).single();",
+            "    // BUG: Diagnostic contains:",
+            "    Flux.just(1).reduce(2, Integer::sum).single();",
+            "",
             "    // BUG: Diagnostic contains:",
-            "    Flux.just().last().defaultIfEmpty(1);",
+            "    Mono.just(1).defaultIfEmpty(1).defaultIfEmpty(2);",
             "    // BUG: Diagnostic contains:",
-            "    Flux.just().reduceWith(() -> 1, (x, y) -> x).single();",
+            "    Mono.just(1).hasElement().single();",
             "    // BUG: Diagnostic contains:",
-            "    Flux.just().single().switchIfEmpty(Mono.just(1));",
+            "    Mono.just(1).single().switchIfEmpty(Mono.just(2));",
             "  }",
             "}")
         .doTest();