diff --git a/docs/rh-log.txt b/docs/rh-log.txt
index 86d725d6a7..927f5428d8 100644
--- a/docs/rh-log.txt
+++ b/docs/rh-log.txt
@@ -1,3 +1,8 @@
+October 20, 2006
+- Fixed: ExpData::EvalConst() did not NULL the children pointers for binary
+  operators after deleting them, so ~ExpData() would try to delete them again
+  later.
+
 October 19, 2006
 - Added a new MapMarker actor. Instead of appearing in the 3D view, it appears
   on the automap instead. If its first argument is zero, the map marker itself
diff --git a/src/thingdef_exp.cpp b/src/thingdef_exp.cpp
index 2ae21248a9..eaf6a36875 100644
--- a/src/thingdef_exp.cpp
+++ b/src/thingdef_exp.cpp
@@ -309,8 +309,8 @@ struct ExpData
 			{
 				Value = EvalExpression (this, NULL);
 				Type = EX_Const;
-				delete Children[0];
-				delete Children[1];
+				delete Children[0]; Children[0] = NULL;
+				delete Children[1]; Children[1] = NULL;
 			}
 		}
 	}