diff --git a/sources/test/SessionTest.cpp b/sources/test/SessionTest.cpp
index 49fbf67..cd9df38 100644
--- a/sources/test/SessionTest.cpp
+++ b/sources/test/SessionTest.cpp
@@ -527,7 +527,7 @@ void SessionTest::takeSingleSellerToExchange(SellerPeer & peer) {
     PeerToStartDownloadInformationMap<ID> map = downloadInformationMap(v);
 
     // Start download
-    session->startDownloading(contractTx, map);
+    session->startDownloading(contractTx, map, nextPiecePicker);
 
     // make sure contract was announced to only relevant peers
     peer.contractAnnounced();
@@ -549,3 +549,12 @@ void SessionTest::assertSellerInvited(const SellerPeer & peer) {
     EXPECT_EQ(m2.index(), peer.sellerTermsIndex);
 
 }
+
+
+int SessionTest::nextPiecePicker(const std::vector<detail::Piece<ID>>* pieces) {
+  for(uint32_t i = 0;i < pieces->size();i++)
+    if(pieces->at(i).state() == PieceState::unassigned)
+      return i;
+
+  throw exception::NoPieceAvailableException();
+}
diff --git a/sources/test/SessionTest.hpp b/sources/test/SessionTest.hpp
index b585f1f..d675a4d 100644
--- a/sources/test/SessionTest.hpp
+++ b/sources/test/SessionTest.hpp
@@ -159,7 +159,7 @@ class SessionTest : public ::testing::Test {
             return joiningContract;
         }
 
-        void contractAnnounced() {            
+        void contractAnnounced() {
             auto slot = spy->sendReadyCallbackSlot;
             EXPECT_TRUE((int)slot.size() > 0);
             ready = std::get<0>(slot.front());
@@ -233,6 +233,8 @@ class SessionTest : public ::testing::Test {
     bool hasPendingFullPieceRequest(const std::vector<SellerPeer> &);
     void takeSingleSellerToExchange(SellerPeer &);
     void assertSellerInvited(const SellerPeer &);
+
+    static int nextPiecePicker(const std::vector<detail::Piece<ID>>* pieces);
 };
 
 #endif // TEST_HPP
diff --git a/sources/test/test_main.cpp b/sources/test/test_main.cpp
index 0edf246..eb59cbb 100644
--- a/sources/test/test_main.cpp
+++ b/sources/test/test_main.cpp
@@ -485,7 +485,7 @@ TEST_F(SessionTest, buying)
     PeerToStartDownloadInformationMap<ID> map = downloadInformationMap(v);
 
     // Start download
-    session->startDownloading(contractTx, map);
+    session->startDownloading(contractTx, map, SessionTest::nextPiecePicker);
 
     // make sure contract was announced to only relevant peers
     first.contractAnnounced();