diff --git a/include/list b/include/list
index 6040e7a..c6000c9 100644
--- a/include/list
+++ b/include/list
@@ -394,7 +394,7 @@
 #endif
     }
     _LIBCPP_INLINE_VISIBILITY
-    __list_const_iterator(__list_iterator<_Tp, _VoidPtr> __p) _NOEXCEPT
+    __list_const_iterator(const __list_iterator<_Tp, _VoidPtr>& __p) _NOEXCEPT
         : __ptr_(__p.__ptr_)
     {
 #if _LIBCPP_DEBUG_LEVEL >= 2
diff --git a/src/debug.cpp b/src/debug.cpp
index 2d4b094..06040af 100644
--- a/src/debug.cpp
+++ b/src/debug.cpp
@@ -110,8 +110,7 @@
 {
     RLock _(mut());
     __i_node* i = __find_iterator(__i);
-    _LIBCPP_ASSERT(i != nullptr, "iterator constructed in translation unit with debug mode not enabled."
-                   "  #define _LIBCPP_DEBUG2 1 for that translation unit.");
+    _LIBCPP_ASSERT(i != nullptr, "iterator not found in debug database.");
     return i->__c_ != nullptr ? i->__c_->__c_ : nullptr;
 }
 
@@ -302,7 +301,7 @@
     __i_node* i = __find_iterator(__i);
     __i_node* i0 = __find_iterator(__i0);
     __c_node* c0 = i0 != nullptr ? i0->__c_ : nullptr;
-    if (i == nullptr && c0 != nullptr)
+    if (i == nullptr && i0 != nullptr)
         i = __insert_iterator(__i);
     __c_node* c = i != nullptr ? i->__c_ : nullptr;
     if (c != c0)
diff --git a/test/containers/sequences/list/list.special/db_swap_1.pass.cpp b/test/containers/sequences/list/list.special/db_swap_1.pass.cpp
new file mode 100644
index 0000000..12730c2
--- /dev/null
+++ b/test/containers/sequences/list/list.special/db_swap_1.pass.cpp
@@ -0,0 +1,42 @@
+//===----------------------------------------------------------------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is dual licensed under the MIT and the University of Illinois Open
+// Source Licenses. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+// <list>
+
+// template <class T, class Alloc>
+//   void swap(list<T,Alloc>& x, list<T,Alloc>& y);
+
+#if _LIBCPP_DEBUG2 >= 1
+#define _LIBCPP_ASSERT(x, m) ((x) ? (void)0 : std::exit(0))
+#endif
+
+#include <list>
+#include <cassert>
+
+#include <__debug>
+
+int main()
+{
+#if _LIBCPP_DEBUG2 >= 1
+    {
+        int a1[] = {1, 3, 7, 9, 10};
+        int a2[] = {0, 2, 4, 5, 6, 8, 11};
+        std::list<int> c1(a1, a1+sizeof(a1)/sizeof(a1[0]));
+        std::list<int> c2(a2, a2+sizeof(a2)/sizeof(a2[0]));
+        std::list<int>::iterator i1 = c1.begin();
+        std::list<int>::iterator i2 = c2.begin();
+        swap(c1, c2);
+        c1.erase(i2);
+        c2.erase(i1);
+        std::list<int>::iterator j = i1;
+        c1.erase(i1);
+        assert(false);
+    }
+#endif
+}