diff --git a/src/dthinker.cpp b/src/dthinker.cpp
index fd20a4e79..11ba54dbc 100644
--- a/src/dthinker.cpp
+++ b/src/dthinker.cpp
@@ -675,6 +675,9 @@ DThinker *FThinkerIterator::Next (bool exact)
 					{
 						return thinker;
 					}
+					// This can actually happen when a Destroy call on 'thinker' happens to destroy 'm_CurrThinker'.
+					// In that case there is no chance to recover, we have to terminate the iteration of this list.
+					if (m_CurrThinker == nullptr) break;
 				}
 			}
 			if ((m_SearchingFresh = !m_SearchingFresh))