diff --git a/app/src/main/java/at/bitfire/davdroid/DavUtils.java b/app/src/main/java/at/bitfire/davdroid/DavUtils.java
index 8664f467..a8d04bf0 100644
--- a/app/src/main/java/at/bitfire/davdroid/DavUtils.java
+++ b/app/src/main/java/at/bitfire/davdroid/DavUtils.java
@@ -12,11 +12,18 @@ import android.support.annotation.NonNull;
 
 import org.apache.commons.lang3.StringUtils;
 
+import java.io.ByteArrayOutputStream;
+import java.io.IOException;
+import java.io.OutputStream;
 import java.util.Collections;
 import java.util.LinkedList;
 import java.util.List;
 
+import lombok.Cleanup;
 import okhttp3.HttpUrl;
+import okhttp3.MediaType;
+import okhttp3.RequestBody;
+import okio.BufferedSink;
 
 public class DavUtils {
 
@@ -26,6 +33,21 @@ public class DavUtils {
         return String.format("#%06X%02X", color, alpha);
     }
 
+    public static RequestBody requestBody(final MediaType mediaType, @NonNull final ByteArrayOutputStream dataStream) throws IOException {
+        return new RequestBody() {
+            @Override
+            public MediaType contentType() {
+                return mediaType;
+            }
+
+            @Override
+            public void writeTo(BufferedSink sink) throws IOException {
+                @Cleanup OutputStream os = sink.outputStream();
+                dataStream.writeTo(os);
+            }
+        };
+    }
+
     public static String lastSegmentOfUrl(@NonNull String url) {
         // the list returned by HttpUrl.pathSegments() is unmodifiable, so we have to create a copy
         List<String> segments = new LinkedList<>(HttpUrl.parse(url).pathSegments());
diff --git a/app/src/main/java/at/bitfire/davdroid/syncadapter/CalendarSyncManager.java b/app/src/main/java/at/bitfire/davdroid/syncadapter/CalendarSyncManager.java
index 488ac52e..592d9b4b 100644
--- a/app/src/main/java/at/bitfire/davdroid/syncadapter/CalendarSyncManager.java
+++ b/app/src/main/java/at/bitfire/davdroid/syncadapter/CalendarSyncManager.java
@@ -39,6 +39,7 @@ import at.bitfire.davdroid.AccountSettings;
 import at.bitfire.davdroid.App;
 import at.bitfire.davdroid.ArrayUtils;
 import at.bitfire.davdroid.Constants;
+import at.bitfire.davdroid.DavUtils;
 import at.bitfire.davdroid.InvalidAccountException;
 import at.bitfire.davdroid.R;
 import at.bitfire.davdroid.resource.LocalCalendar;
@@ -97,10 +98,7 @@ public class CalendarSyncManager extends SyncManager {
     protected RequestBody prepareUpload(LocalResource resource) throws IOException, CalendarStorageException {
         LocalEvent local = (LocalEvent)resource;
         App.log.log(Level.FINE, "Preparing upload of event " + local.getFileName(), new Object[] { local.getEvent() });
-        return RequestBody.create(
-                DavCalendar.MIME_ICALENDAR,
-                local.getEvent().toStream().toByteArray()
-        );
+        return DavUtils.requestBody(DavCalendar.MIME_ICALENDAR, local.getEvent().toStream());
     }
 
     @Override
diff --git a/app/src/main/java/at/bitfire/davdroid/syncadapter/ContactsSyncManager.java b/app/src/main/java/at/bitfire/davdroid/syncadapter/ContactsSyncManager.java
index 06f2474c..4d055e9a 100644
--- a/app/src/main/java/at/bitfire/davdroid/syncadapter/ContactsSyncManager.java
+++ b/app/src/main/java/at/bitfire/davdroid/syncadapter/ContactsSyncManager.java
@@ -41,6 +41,7 @@ import at.bitfire.davdroid.AccountSettings;
 import at.bitfire.davdroid.App;
 import at.bitfire.davdroid.ArrayUtils;
 import at.bitfire.davdroid.Constants;
+import at.bitfire.davdroid.DavUtils;
 import at.bitfire.davdroid.HttpClient;
 import at.bitfire.davdroid.InvalidAccountException;
 import at.bitfire.davdroid.R;
@@ -131,9 +132,9 @@ public class ContactsSyncManager extends SyncManager {
     protected RequestBody prepareUpload(LocalResource resource) throws IOException, ContactsStorageException {
         LocalContact local = (LocalContact)resource;
         App.log.log(Level.FINE, "Preparing upload of contact " + local.getFileName(), new Object[] { local.getContact() });
-        return RequestBody.create(
+        return DavUtils.requestBody(
                 hasVCard4 ? DavAddressBook.MIME_VCARD4 : DavAddressBook.MIME_VCARD3_UTF8,
-                local.getContact().toStream(hasVCard4 ? VCardVersion.V4_0 : VCardVersion.V3_0).toByteArray()
+                local.getContact().toStream(hasVCard4 ? VCardVersion.V4_0 : VCardVersion.V3_0)
         );
     }
 
diff --git a/app/src/main/java/at/bitfire/davdroid/syncadapter/TasksSyncManager.java b/app/src/main/java/at/bitfire/davdroid/syncadapter/TasksSyncManager.java
index 518d365a..fc64748a 100644
--- a/app/src/main/java/at/bitfire/davdroid/syncadapter/TasksSyncManager.java
+++ b/app/src/main/java/at/bitfire/davdroid/syncadapter/TasksSyncManager.java
@@ -19,6 +19,7 @@ import org.apache.commons.lang3.StringUtils;
 import java.io.ByteArrayInputStream;
 import java.io.IOException;
 import java.io.InputStream;
+import java.io.PipedInputStream;
 import java.nio.charset.Charset;
 import java.util.HashMap;
 import java.util.LinkedList;
@@ -37,6 +38,7 @@ import at.bitfire.davdroid.AccountSettings;
 import at.bitfire.davdroid.App;
 import at.bitfire.davdroid.ArrayUtils;
 import at.bitfire.davdroid.Constants;
+import at.bitfire.davdroid.DavUtils;
 import at.bitfire.davdroid.InvalidAccountException;
 import at.bitfire.davdroid.R;
 import at.bitfire.davdroid.resource.LocalResource;
@@ -91,10 +93,7 @@ public class TasksSyncManager extends SyncManager {
     protected RequestBody prepareUpload(LocalResource resource) throws IOException, CalendarStorageException {
         LocalTask local = (LocalTask)resource;
         App.log.log(Level.FINE, "Preparing upload of task " + local.getFileName(), new Object[] { local.getTask() });
-        return RequestBody.create(
-                DavCalendar.MIME_ICALENDAR,
-                local.getTask().toStream().toByteArray()
-        );
+        return DavUtils.requestBody(DavCalendar.MIME_ICALENDAR, local.getTask().toStream());
     }
 
     @Override