diff --git a/nullaway/src/main/java/com/uber/nullaway/NullAway.java b/nullaway/src/main/java/com/uber/nullaway/NullAway.java
index 4104da418d..3d17824579 100644
--- a/nullaway/src/main/java/com/uber/nullaway/NullAway.java
+++ b/nullaway/src/main/java/com/uber/nullaway/NullAway.java
@@ -639,12 +639,14 @@ private Description checkReturnExpression(
       return Description.NO_MATCH;
     }
     if (mayBeNullExpr(state, retExpr)) {
-      String message = "returning @Nullable expression from method with @NonNull return type";
+      final ErrorMessage errorMessage =
+          new ErrorMessage(
+              MessageTypes.RETURN_NULLABLE,
+              "returning @Nullable expression from method with @NonNull return type");
+      handler.onPrepareErrorMessage(retExpr, state, errorMessage);
+
       return errorBuilder.createErrorDescriptionForNullAssignment(
-          new ErrorMessage(MessageTypes.RETURN_NULLABLE, message),
-          retExpr,
-          state.getPath(),
-          buildDescription(tree));
+          errorMessage, retExpr, state.getPath(), buildDescription(tree));
     }
     return Description.NO_MATCH;
   }
diff --git a/nullaway/src/test/java/com/uber/nullaway/NullAwayTest.java b/nullaway/src/test/java/com/uber/nullaway/NullAwayTest.java
index d167482205..3010628a26 100644
--- a/nullaway/src/test/java/com/uber/nullaway/NullAwayTest.java
+++ b/nullaway/src/test/java/com/uber/nullaway/NullAwayTest.java
@@ -1551,6 +1551,70 @@ public void OptionalEmptinessUncheckedTest() {
         .doTest();
   }
 
+  @Test
+  public void OptionalEmptinessRxPositiveTest() {
+    compilationHelper
+        .setArgs(
+            Arrays.asList(
+                "-d",
+                temporaryFolder.getRoot().getAbsolutePath(),
+                "-XepOpt:NullAway:AnnotatedPackages=com.uber,io.reactivex",
+                "-XepOpt:NullAway:UnannotatedSubPackages=com.uber.lib.unannotated",
+                "-XepOpt:NullAway:CheckOptionalEmptiness=true"))
+        .addSourceLines(
+            "TestPositive.java",
+            "package com.uber;",
+            "import java.util.Optional;",
+            "import io.reactivex.Observable;",
+            "public class TestPositive {",
+            "  private static boolean perhaps() { return Math.random() > 0.5; }",
+            "  void foo(Observable<Optional<String>> observable) {",
+            "     observable",
+            "           .filter(optional -> optional.isPresent() || perhaps())",
+            "           // BUG: Diagnostic contains: Optional optional can be empty",
+            "           .map(optional -> optional.get().toString());",
+            "     observable",
+            "           .filter(optional -> optional.isPresent() || perhaps())",
+            "           // BUG: Diagnostic contains: Optional optional can be empty",
+            "           .map(optional -> optional.get())",
+            "           .map(irr -> irr.toString());",
+            "     }",
+            "}")
+        .doTest();
+  }
+
+  @Test
+  public void OptionalEmptinessRxNegativeTest() {
+    compilationHelper
+        .setArgs(
+            Arrays.asList(
+                "-d",
+                temporaryFolder.getRoot().getAbsolutePath(),
+                "-XepOpt:NullAway:AnnotatedPackages=com.uber",
+                "-XepOpt:NullAway:UnannotatedSubPackages=com.uber.lib.unannotated",
+                "-XepOpt:NullAway:CheckOptionalEmptiness=true"))
+        .addSourceLines(
+            "TestNegative.java",
+            "package com.uber;",
+            "import java.util.Optional;",
+            "import io.reactivex.Observable;",
+            "public class TestNegative {",
+            "  private static boolean perhaps() { return Math.random() > 0.5; }",
+            "  void foo(Observable<Optional<String>> observable) {",
+            "     observable",
+            "           .filter(optional -> optional.isPresent())",
+            "           .map(optional -> optional.get().toString());",
+            "     observable",
+            "           .filter(optional -> optional.isPresent() && perhaps())",
+            "           .map(optional -> optional.get().toString());",
+            "     observable",
+            "           .filter(optional -> optional.isPresent() && perhaps())",
+            "           .map(optional -> optional.get());",
+            "     }",
+            "}")
+        .doTest();
+  }
+
   @Test
   public void testCastToNonNull() {
     compilationHelper