diff --git a/webclient/grpc/src/main/java/io/helidon/webclient/grpc/GrpcBaseClientCall.java b/webclient/grpc/src/main/java/io/helidon/webclient/grpc/GrpcBaseClientCall.java
index 06aa4d188e2..37b79065523 100644
--- a/webclient/grpc/src/main/java/io/helidon/webclient/grpc/GrpcBaseClientCall.java
+++ b/webclient/grpc/src/main/java/io/helidon/webclient/grpc/GrpcBaseClientCall.java
@@ -16,7 +16,10 @@
 
 package io.helidon.webclient.grpc;
 
+import java.io.ByteArrayOutputStream;
+import java.io.IOException;
 import java.io.InputStream;
+import java.io.UncheckedIOException;
 import java.time.Duration;
 import java.util.Collections;
 import java.util.concurrent.Executor;
@@ -214,4 +217,14 @@ public int read() {
             }
         });
     }
+
+    protected byte[] serializeMessage(ReqT message) {
+        ByteArrayOutputStream baos = new ByteArrayOutputStream(BUFFER_SIZE_BYTES);
+        try (InputStream is = requestMarshaller().stream(message)) {
+            is.transferTo(baos);
+        } catch (IOException e) {
+            throw new UncheckedIOException(e);
+        }
+        return baos.toByteArray();
+    }
 }
diff --git a/webclient/grpc/src/main/java/io/helidon/webclient/grpc/GrpcClientCall.java b/webclient/grpc/src/main/java/io/helidon/webclient/grpc/GrpcClientCall.java
index 13549c464cd..56a836e22b9 100644
--- a/webclient/grpc/src/main/java/io/helidon/webclient/grpc/GrpcClientCall.java
+++ b/webclient/grpc/src/main/java/io/helidon/webclient/grpc/GrpcClientCall.java
@@ -16,10 +16,6 @@
 
 package io.helidon.webclient.grpc;
 
-import java.io.ByteArrayOutputStream;
-import java.io.IOException;
-import java.io.InputStream;
-import java.io.UncheckedIOException;
 import java.util.concurrent.CountDownLatch;
 import java.util.concurrent.ExecutorService;
 import java.util.concurrent.Future;
@@ -93,16 +89,8 @@ public void halfClose() {
     public void sendMessage(ReqT message) {
         socket().log(LOGGER, DEBUG, "sendMessage called");
 
-        // serialize message using a marshaller
-        ByteArrayOutputStream baos = new ByteArrayOutputStream(BUFFER_SIZE_BYTES);
-        try (InputStream is = requestMarshaller().stream(message)) {
-            is.transferTo(baos);
-        } catch (IOException e) {
-            throw new UncheckedIOException(e);
-        }
-        byte[] serialized = baos.toByteArray();
-
-        // queue data message and start writer
+        // serialize and queue message for writing
+        byte[] serialized = serializeMessage(message);
         BufferData messageData = BufferData.createReadOnly(serialized, 0, serialized.length);
         BufferData headerData = BufferData.create(5);
         headerData.writeInt8(0);                                // no compression
diff --git a/webclient/grpc/src/main/java/io/helidon/webclient/grpc/GrpcUnaryClientCall.java b/webclient/grpc/src/main/java/io/helidon/webclient/grpc/GrpcUnaryClientCall.java
index e2c9a87fd81..ac3291bd248 100644
--- a/webclient/grpc/src/main/java/io/helidon/webclient/grpc/GrpcUnaryClientCall.java
+++ b/webclient/grpc/src/main/java/io/helidon/webclient/grpc/GrpcUnaryClientCall.java
@@ -77,8 +77,9 @@ public void sendMessage(ReqT message) {
             return;
         }
 
-        BufferData messageData = BufferData.growing(BUFFER_SIZE_BYTES);
-        messageData.readFrom(requestMarshaller().stream(message));
+        // serialize and write message
+        byte[] serialized = serializeMessage(message);
+        BufferData messageData = BufferData.createReadOnly(serialized, 0, serialized.length);
         BufferData headerData = BufferData.create(5);
         headerData.writeInt8(0);                                // no compression
         headerData.writeUnsignedInt32(messageData.available());         // length prefixed
diff --git a/webclient/tests/grpc/src/test/java/io/helidon/webclient/grpc/tests/GrpcStubTest.java b/webclient/tests/grpc/src/test/java/io/helidon/webclient/grpc/tests/GrpcStubTest.java
index 935bb22aca7..e1701dca81e 100644
--- a/webclient/tests/grpc/src/test/java/io/helidon/webclient/grpc/tests/GrpcStubTest.java
+++ b/webclient/tests/grpc/src/test/java/io/helidon/webclient/grpc/tests/GrpcStubTest.java
@@ -16,6 +16,7 @@
 
 package io.helidon.webclient.grpc.tests;
 
+import java.nio.CharBuffer;
 import java.nio.charset.StandardCharsets;
 import java.util.Iterator;
 import java.util.Random;
@@ -23,7 +24,6 @@
 import java.util.concurrent.ExecutionException;
 import java.util.concurrent.TimeUnit;
 import java.util.concurrent.TimeoutException;
-import java.util.stream.IntStream;
 
 import io.helidon.common.configurable.Resource;
 import io.helidon.common.tls.Tls;
@@ -70,6 +70,15 @@ void testUnaryUpper() {
         assertThat(res.getText(), is("HELLO"));
     }
 
+    @Test
+    void tesUnaryUpperLongString() {
+        GrpcClient grpcClient = webClient.client(GrpcClient.PROTOCOL);
+        StringServiceGrpc.StringServiceBlockingStub service = StringServiceGrpc.newBlockingStub(grpcClient.channel());
+        String s = CharBuffer.allocate(2000).toString().replace('\0', 'a');
+        Strings.StringMessage res = service.upper(newStringMessage(s));
+        assertThat(res.getText(), is(s.toUpperCase()));
+    }
+
     @Test
     void testUnaryUpperAsync() throws ExecutionException, InterruptedException, TimeoutException {
         GrpcClient grpcClient = webClient.client(GrpcClient.PROTOCOL);