diff --git a/headers/private/app/PortLink.h b/headers/private/app/PortLink.h
index e285374334..68241a806d 100644
--- a/headers/private/app/PortLink.h
+++ b/headers/private/app/PortLink.h
@@ -57,6 +57,7 @@ public:
 		if (4096 - fSendPosition > size){
 			memcpy(fSendBuffer + fSendPosition, &data, size);
 			fSendPosition += size;
+			*fDataSize+=size;
 			return B_OK;
 		}
 		return B_NO_MEMORY;