diff --git a/tck/src/main/java/org/reactivestreams/tck/IdentityProcessorVerification.java b/tck/src/main/java/org/reactivestreams/tck/IdentityProcessorVerification.java
index ed972aa0..5efe6e27 100644
--- a/tck/src/main/java/org/reactivestreams/tck/IdentityProcessorVerification.java
+++ b/tck/src/main/java/org/reactivestreams/tck/IdentityProcessorVerification.java
@@ -370,6 +370,11 @@ public void required_spec309_requestZeroMustSignalIllegalArgumentException() thr
   public void required_spec309_requestNegativeNumberMustSignalIllegalArgumentException() throws Throwable {
     publisherVerification.required_spec309_requestNegativeNumberMustSignalIllegalArgumentException();
   }
+  
+  @Override @Test
+  public void optional_spec309_requestNegativeNumberMaySignalIllegalArgumentExceptionWithSpecificMessage() throws Throwable {
+    publisherVerification.optional_spec309_requestNegativeNumberMaySignalIllegalArgumentExceptionWithSpecificMessage();
+  }
 
   @Override @Test
   public void required_spec312_cancelMustMakeThePublisherToEventuallyStopSignaling() throws Throwable {
diff --git a/tck/src/main/java/org/reactivestreams/tck/PublisherVerification.java b/tck/src/main/java/org/reactivestreams/tck/PublisherVerification.java
index e9011b9d..eb6f9344 100644
--- a/tck/src/main/java/org/reactivestreams/tck/PublisherVerification.java
+++ b/tck/src/main/java/org/reactivestreams/tck/PublisherVerification.java
@@ -896,7 +896,7 @@ public void required_spec309_requestZeroMustSignalIllegalArgumentException() thr
       @Override public void run(Publisher<T> pub) throws Throwable {
         final ManualSubscriber<T> sub = env.newManualSubscriber(pub);
         sub.request(0);
-        sub.expectErrorWithMessage(IllegalArgumentException.class, "3.9"); // we do require implementations to mention the rule number at the very least
+        sub.expectError(IllegalArgumentException.class);
       }
     });
   }
@@ -909,7 +909,22 @@ public void run(Publisher<T> pub) throws Throwable {
         final ManualSubscriber<T> sub = env.newManualSubscriber(pub);
         final Random r = new Random();
         sub.request(-r.nextInt(Integer.MAX_VALUE) - 1);
-        sub.expectErrorWithMessage(IllegalArgumentException.class, "3.9"); // we do require implementations to mention the rule number at the very least
+        // we do require implementations to mention the rule number at the very least, or mentioning that the non-negative request is the problem
+        sub.expectError(IllegalArgumentException.class); 
+      }
+    });
+  }
+
+  @Override @Test
+  public void optional_spec309_requestNegativeNumberMaySignalIllegalArgumentExceptionWithSpecificMessage() throws Throwable {
+    optionalActivePublisherTest(10, false, new PublisherTestRun<T>() {
+      @Override
+      public void run(Publisher<T> pub) throws Throwable {
+        final ManualSubscriber<T> sub = env.newManualSubscriber(pub);
+        final Random r = new Random();
+        sub.request(-r.nextInt(Integer.MAX_VALUE) - 1);
+        // we do require implementations to mention the rule number at the very least, or mentioning that the non-negative request is the problem
+        sub.expectErrorWithMessage(IllegalArgumentException.class, Arrays.asList("3.9", "non-positive subscription request", "negative subscription request")); 
       }
     });
   }
diff --git a/tck/src/main/java/org/reactivestreams/tck/TestEnvironment.java b/tck/src/main/java/org/reactivestreams/tck/TestEnvironment.java
index 86649058..e7474d59 100644
--- a/tck/src/main/java/org/reactivestreams/tck/TestEnvironment.java
+++ b/tck/src/main/java/org/reactivestreams/tck/TestEnvironment.java
@@ -17,6 +17,7 @@
 import org.reactivestreams.tck.support.SubscriberBufferOverflowException;
 import org.reactivestreams.tck.support.Optional;
 
+import java.util.Collections;
 import java.util.LinkedList;
 import java.util.List;
 import java.util.concurrent.ArrayBlockingQueue;
@@ -513,14 +514,24 @@ public void expectCompletion(long timeoutMillis, String errorMsg) throws Interru
     public <E extends Throwable> void expectErrorWithMessage(Class<E> expected, String requiredMessagePart) throws Exception {
       expectErrorWithMessage(expected, requiredMessagePart, env.defaultTimeoutMillis());
     }
+    public <E extends Throwable> void expectErrorWithMessage(Class<E> expected, List<String> requiredMessagePartAlternatives) throws Exception {
+      expectErrorWithMessage(expected, requiredMessagePartAlternatives, env.defaultTimeoutMillis());
+    }
 
     @SuppressWarnings("ThrowableResultOfMethodCallIgnored")
     public <E extends Throwable> void expectErrorWithMessage(Class<E> expected, String requiredMessagePart, long timeoutMillis) throws Exception {
+      expectErrorWithMessage(expected, Collections.singletonList(requiredMessagePart), timeoutMillis);
+    }
+    public <E extends Throwable> void expectErrorWithMessage(Class<E> expected, List<String> requiredMessagePartAlternatives, long timeoutMillis) throws Exception {
       final E err = expectError(expected, timeoutMillis);
       final String message = err.getMessage();
-      assertTrue(message.contains(requiredMessagePart),
+      
+      boolean contains = false;
+      for (String requiredMessagePart : requiredMessagePartAlternatives) 
+        if (message.contains(requiredMessagePart)) contains = true; // not short-circuting loop, it is expected to
+      assertTrue(contains,
                  String.format("Got expected exception [%s] but missing message part [%s], was: %s",
-                               err.getClass(), requiredMessagePart, err.getMessage()));
+                               err.getClass(), "anyOf: " + requiredMessagePartAlternatives, err.getMessage()));
     }
 
     public <E extends Throwable> E expectError(Class<E> expected) throws Exception {
diff --git a/tck/src/main/java/org/reactivestreams/tck/support/PublisherVerificationRules.java b/tck/src/main/java/org/reactivestreams/tck/support/PublisherVerificationRules.java
index cd3cf032..e429ec30 100644
--- a/tck/src/main/java/org/reactivestreams/tck/support/PublisherVerificationRules.java
+++ b/tck/src/main/java/org/reactivestreams/tck/support/PublisherVerificationRules.java
@@ -471,7 +471,7 @@ public interface PublisherVerificationRules {
   void required_spec307_afterSubscriptionIsCancelledAdditionalCancelationsMustBeNops() throws Throwable;
   /**
    * Asks for a short {@code Publisher} (length 10) and issues a {@code request(0)} which should trigger an {@code onError} call
-   * with an {@code IllegalArgumentException} and the message containing the string "3.9" (reference to the rule number).
+   * with an {@code IllegalArgumentException}.
    * <p>
    * <b>Verifies rule:</b> <a href='https://github.com/reactive-streams/reactive-streams-jvm#3.9'>3.9</a>
    * <p>
@@ -495,8 +495,8 @@ public interface PublisherVerificationRules {
    */
   void required_spec309_requestZeroMustSignalIllegalArgumentException() throws Throwable;
   /**
-   * Asks for a short {@code Publisher} (length 10) and issues a random, negative {@code request()} call which should trigger an {@code onError} call
-   * with an {@code IllegalArgumentException} and the message containing the string "3.9" (reference to the rule number).
+   * Asks for a short {@code Publisher} (length 10) and issues a random, negative {@code request()} call which should 
+   * trigger an {@code onError} call with an {@code IllegalArgumentException}. 
    * <p>
    * <b>Verifies rule:</b> <a href='https://github.com/reactive-streams/reactive-streams-jvm#3.9'>3.9</a>
    * <p>
@@ -519,6 +519,31 @@ public interface PublisherVerificationRules {
    * </ul>
    */
   void required_spec309_requestNegativeNumberMustSignalIllegalArgumentException() throws Throwable;
+  /**
+   * Asks for a short {@code Publisher} (length 10) and issues a random, negative {@code request()} call which should 
+   * trigger an {@code onError} call with an {@code IllegalArgumentException}. 
+   * <p>
+   * <b>Verifies rule:</b> <a href='https://github.com/reactive-streams/reactive-streams-jvm#3.9'>3.9</a>
+   * <p>
+   * The test is not executed if {@link org.reactivestreams.tck.PublisherVerification#maxElementsFromPublisher()} is less than 10.
+   * <p>
+   * Note that this test expects the {@code IllegalArgumentException} being signalled through {@code onError}, not by
+   * throwing from {@code request()} (which is also forbidden) or signalling the error by any other means (i.e., through the
+   * {@code Thread.currentThread().getUncaughtExceptionHandler()} for example).
+   * <p>
+   * Note also that requesting and emission may happen concurrently and honoring this rule may require extra coordination within
+   * the {@code Publisher}.
+   * <p>
+   * If this test fails, the following could be checked within the {@code Publisher} implementation:
+   * <ul>
+   * <li>the {@code TestEnvironment} has large enough timeout specified in case the {@code Publisher} has some time-delay behavior,</li>
+   * <li>make sure the {@link #required_createPublisher1MustProduceAStreamOfExactly1Element()} and {@link #required_createPublisher3MustProduceAStreamOfExactly3Elements()} tests pass,</li>
+   * <li>the {@code Publisher} can emit an {@code onError} in this particular case, even if there was no prior and legal
+   * {@code request} call and even if the {@code Publisher} would like to emit items first before emitting an {@code onError}
+   * in general.
+   * </ul>
+   */
+  void optional_spec309_requestNegativeNumberMaySignalIllegalArgumentExceptionWithSpecificMessage() throws Throwable;
   /**
    * Asks for a short {@code Publisher} (length 20), requests some items (less than the length), consumes one item then
    * cancels the sequence and verifies the publisher emitted at most the requested amount and stopped emitting (or terminated). 
diff --git a/tck/src/test/java/org/reactivestreams/tck/PublisherVerificationTest.java b/tck/src/test/java/org/reactivestreams/tck/PublisherVerificationTest.java
index 87ef07ca..52270518 100644
--- a/tck/src/test/java/org/reactivestreams/tck/PublisherVerificationTest.java
+++ b/tck/src/test/java/org/reactivestreams/tck/PublisherVerificationTest.java
@@ -481,6 +481,27 @@ public void required_spec309_requestZeroMustSignalIllegalArgumentException_shoul
     }, "Expected onError");
   }
 
+  @Test
+  public void required_spec309_requestZeroMustSignalIllegalArgumentException_shouldPass() throws Throwable {
+    customPublisherVerification(new Publisher<Integer>() {
+      @Override
+      public void subscribe(final Subscriber<? super Integer> s) {
+        s.onSubscribe(new Subscription() {
+          @Override
+          public void request(long n) {
+            // we error out with any message, it does not have to contain any specific wording
+            if (n <= 0) s.onError(new IllegalArgumentException("Illegal request value detected!"));
+          }
+
+          @Override
+          public void cancel() {
+            // noop
+          }
+        });
+      }
+    }).required_spec309_requestZeroMustSignalIllegalArgumentException();
+  }
+
   @Test
   public void required_spec309_requestNegativeNumberMustSignalIllegalArgumentException_shouldFailBy_expectingOnError() throws Throwable {
     requireTestFailure(new ThrowingRunnable() {