diff --git a/src/main.cpp b/src/main.cpp
index 379ca3ef7..f90f03801 100644
--- a/src/main.cpp
+++ b/src/main.cpp
@@ -3373,7 +3373,7 @@ void static ProcessGetData(CNode* pfrom)
                 {
                     // Send block from disk
                     CBlock block;
-                    ReadBlockFromDisk(block, (*mi).second);
+                    assert(ReadBlockFromDisk(block, (*mi).second));
                     if (inv.type == MSG_BLOCK)
                         pfrom->PushMessage("block", block);
                     else // MSG_FILTERED_BLOCK)