diff --git a/src/mirall/propagator_qnam.cpp b/src/mirall/propagator_qnam.cpp
index 61404a875..f3b3bf44b 100644
--- a/src/mirall/propagator_qnam.cpp
+++ b/src/mirall/propagator_qnam.cpp
@@ -28,7 +28,7 @@
 
 namespace Mirall {
 
-static uint chunkSize() {
+static qint64 chunkSize() {
     static uint chunkSize;
     if (!chunkSize) {
         chunkSize = qgetenv("OWNCLOUD_CHUNK_SIZE").toUInt();
@@ -298,7 +298,7 @@ void PropagateUploadFileQNAM::startNextChunk()
                 currentChunkSize = chunkSize();
             }
         }
-        device = new ChunkDevice(_file, chunkSize() * sendingChunk, currentChunkSize);
+        device = new ChunkDevice(_file, chunkSize() * quint64(sendingChunk), currentChunkSize);
     } else {
         device = _file;
     }