diff --git a/src/scraplang/apply.cpp b/src/scraplang/apply.cpp
index 415854f..c96f639 100644
--- a/src/scraplang/apply.cpp
+++ b/src/scraplang/apply.cpp
@@ -32,6 +32,7 @@
 #include <list>
 #include <functional>
 #include <algorithm>
+#include <cassert>
 
 namespace duck { namespace sl {
 #if defined(APPLY_VERBOSE)
@@ -122,7 +123,7 @@ namespace duck { namespace sl {
 					std::fill_n(
 						std::back_inserter(parOut),
 						std::max(m_expected_size, parOut.size()) - parOut.size(),
-						parOut.front()
+						parOut.back()
 					);
 				}
 				m_retval = std::move(parOut);