diff --git a/google-cloud-storage/src/main/java/com/google/cloud/storage/ParallelCompositeUploadBlobWriteSessionConfig.java b/google-cloud-storage/src/main/java/com/google/cloud/storage/ParallelCompositeUploadBlobWriteSessionConfig.java
index 498947385e..d3f8764aed 100644
--- a/google-cloud-storage/src/main/java/com/google/cloud/storage/ParallelCompositeUploadBlobWriteSessionConfig.java
+++ b/google-cloud-storage/src/main/java/com/google/cloud/storage/ParallelCompositeUploadBlobWriteSessionConfig.java
@@ -1025,7 +1025,9 @@ private ParallelCompositeUploadWriterFactory(
     @Override
     public WritableByteChannelSession<?, BlobInfo> writeSession(
         StorageInternal s, BlobInfo info, Opts<ObjectTargetOpt> opts) {
-      return new PCUSession(s, info, opts);
+      // if crc32cMatch or md5Match were specified, they will already be in opts
+      BlobInfo trimmed = info.toBuilder().clearCrc32c().clearMd5().build();
+      return new PCUSession(s, trimmed, opts);
     }
 
     private final class PCUSession
diff --git a/google-cloud-storage/src/main/java/com/google/cloud/storage/ParallelCompositeUploadWritableByteChannel.java b/google-cloud-storage/src/main/java/com/google/cloud/storage/ParallelCompositeUploadWritableByteChannel.java
index 2bda77d036..464c6b2372 100644
--- a/google-cloud-storage/src/main/java/com/google/cloud/storage/ParallelCompositeUploadWritableByteChannel.java
+++ b/google-cloud-storage/src/main/java/com/google/cloud/storage/ParallelCompositeUploadWritableByteChannel.java
@@ -425,7 +425,7 @@ private ApiFuture<BlobInfo> cleanupParts(BlobInfo finalInfo) {
 
   private BlobInfo definePart(BlobInfo ultimateObject, PartRange partRange, long offset) {
     BlobId id = ultimateObject.getBlobId();
-    BlobInfo.Builder b = ultimateObject.toBuilder();
+    BlobInfo.Builder b = ultimateObject.toBuilder().clearCrc32c().clearMd5();
     String partName = partNamingStrategy.fmtName(id.getName(), partRange);
     b.setBlobId(BlobId.of(id.getBucket(), partName));
     ImmutableMap.Builder<String, String> builder = ImmutableMap.builder();
diff --git a/google-cloud-storage/src/test/java/com/google/cloud/storage/ParallelCompositeUploadWritableByteChannelTest.java b/google-cloud-storage/src/test/java/com/google/cloud/storage/ParallelCompositeUploadWritableByteChannelTest.java
index 14e9ef1ec7..2990aae5dd 100644
--- a/google-cloud-storage/src/test/java/com/google/cloud/storage/ParallelCompositeUploadWritableByteChannelTest.java
+++ b/google-cloud-storage/src/test/java/com/google/cloud/storage/ParallelCompositeUploadWritableByteChannelTest.java
@@ -39,6 +39,7 @@
 import com.google.cloud.storage.UnifiedOpts.ObjectSourceOpt;
 import com.google.cloud.storage.UnifiedOpts.ObjectTargetOpt;
 import com.google.cloud.storage.UnifiedOpts.Opts;
+import com.google.cloud.storage.it.ChecksummedTestContent;
 import com.google.cloud.storage.spi.v1.StorageRpc;
 import com.google.common.base.MoreObjects;
 import com.google.common.base.Preconditions;
@@ -810,6 +811,41 @@ public BlobInfo internalDirectUpload(
     pcu.close();
   }
 
+  @Test
+  public void partDoesNotSpecifyAnyChecksum() throws IOException {
+    FakeStorageInternal storageInternal =
+        new FakeStorageInternal() {
+          @Override
+          public BlobInfo compose(ComposeRequest composeRequest) {
+            BlobInfo target = composeRequest.getTarget();
+            if (target.getBlobId().getName().startsWith(partNamingStrategy.prefix)) {
+              assertThat(target.getCrc32c()).isNull();
+              assertThat(target.getMd5()).isNull();
+            }
+            return super.compose(composeRequest);
+          }
+        };
+    ChecksummedTestContent content = ChecksummedTestContent.gen(bufferCapacity * 3 - 1);
+    ParallelCompositeUploadWritableByteChannel pcu =
+        new ParallelCompositeUploadWritableByteChannel(
+            bufferHandlePool,
+            MoreExecutors.directExecutor(),
+            partNamingStrategy,
+            PartCleanupStrategy.always(),
+            2,
+            b -> b,
+            finalObject,
+            storageInternal,
+            info.toBuilder()
+                .setCrc32c(content.getCrc32cBase64())
+                .setMd5(content.getMd5Base64())
+                .build(),
+            opts);
+    pcu.write(content.asByteBuffer());
+
+    pcu.close();
+  }
+
   @NonNull
   private ParallelCompositeUploadWritableByteChannel defaultPcu(int maxElementsPerCompact) {
     return new ParallelCompositeUploadWritableByteChannel(