diff -Naur brlcad-7.32.4/src/other/stepcode/src/clstepcore/complexSupport.h brlcad-7.32.4.patched/src/other/stepcode/src/clstepcore/complexSupport.h
--- brlcad-7.32.4/src/other/stepcode/src/clstepcore/complexSupport.h	2021-07-28 23:11:47.000000000 -0400
+++ brlcad-7.32.4.patched/src/other/stepcode/src/clstepcore/complexSupport.h	2022-02-25 17:42:27.909342186 -0500
@@ -208,26 +208,26 @@
         // but all we need.
         EntList * firstNot( JoinType );
         EntList * nextNot( JoinType j ) {
-            return next->firstNot( j );
+            return (next) ? next->firstNot(j) : NULL;
         }
         EntList * firstWanted( MatchType );
         EntList * nextWanted( MatchType mat ) {
-            return next->firstWanted( mat );
+            return (next) ? next->firstWanted(mat) : NULL;
         }
         EntList * lastNot( JoinType );
         EntList * prevNot( JoinType j ) {
-            return prev->lastNot( j );
+            return (prev) ? prev->lastNot(j) : NULL;
         }
         EntList * lastWanted( MatchType );
         EntList * prevWanted( MatchType mat ) {
-            return prev->lastWanted( mat );
+            return (prev) ? prev->lastWanted(mat) : NULL;
         }
 
         JoinType join;
         int multiple() {
             return ( join != SIMPLE );
         }
-        EntList * next, *prev;
+        EntList * next = NULL, *prev = NULL;
 
     protected:
         MatchType viable;
diff -Naur brlcad-7.32.4/src/other/stepcode/src/exp2cxx/complexSupport.h brlcad-7.32.4.patched/src/other/stepcode/src/exp2cxx/complexSupport.h
--- brlcad-7.32.4/src/other/stepcode/src/exp2cxx/complexSupport.h	2021-07-28 23:11:48.000000000 -0400
+++ brlcad-7.32.4.patched/src/other/stepcode/src/exp2cxx/complexSupport.h	2022-02-25 17:40:52.465760163 -0500
@@ -162,26 +162,26 @@
         // but all we need.
         EntList * firstNot( JoinType );
         EntList * nextNot( JoinType j ) {
-            return next->firstNot( j );
+            return (next) ? next->firstNot(j) : NULL;
         }
         EntList * firstWanted( MatchType );
         EntList * nextWanted( MatchType mat ) {
-            return next->firstWanted( mat );
+            return (next) ? next->firstWanted(mat) : NULL;
         }
         EntList * lastNot( JoinType );
         EntList * prevNot( JoinType j ) {
-            return prev->lastNot( j );
+            return (prev) ? prev->lastNot(j) : NULL;
         }
         EntList * lastWanted( MatchType );
         EntList * prevWanted( MatchType mat ) {
-            return prev->lastWanted( mat );
+            return (prev) ? prev->lastWanted(mat) : NULL;
         }
 
         JoinType join;
         int multiple() {
             return ( join != SIMPLE );
         }
-        EntList * next, *prev;
+        EntList * next = NULL, *prev = NULL;
 
     protected:
         MatchType viable;