diff --git a/cad/brlcad/files/patch-src_other_stepcode_src_clstepcore_complexSupport.h b/cad/brlcad/files/patch-src_other_stepcode_src_clstepcore_complexSupport.h
new file mode 100644
index 000000000000..393b8ffdc2c5
--- /dev/null
+++ b/cad/brlcad/files/patch-src_other_stepcode_src_clstepcore_complexSupport.h
@@ -0,0 +1,26 @@
+--- src/other/stepcode/src/clstepcore/complexSupport.h.orig	2020-03-12 15:32:36 UTC
++++ src/other/stepcode/src/clstepcore/complexSupport.h
+@@ -182,19 +182,19 @@ class SC_CORE_EXPORT EntList {
+         // but all we need.
+         EntList * firstNot( JoinType );
+         EntList * nextNot( JoinType j ) {
+-            return next->firstNot( j );
++            return next == NULL ? NULL : next->firstNot( j );
+         }
+         EntList * firstWanted( MatchType );
+         EntList * nextWanted( MatchType mat ) {
+-            return next->firstWanted( mat );
++            return next == NULL ? NULL : next->firstWanted( mat );
+         }
+         EntList * lastNot( JoinType );
+         EntList * prevNot( JoinType j ) {
+-            return prev->lastNot( j );
++            return prev == NULL ? NULL : prev->lastNot( j );
+         }
+         EntList * lastWanted( MatchType );
+         EntList * prevWanted( MatchType mat ) {
+-            return prev->lastWanted( mat );
++            return prev == NULL ? NULL : prev->lastWanted( mat );
+         }
+ 
+         JoinType join;
diff --git a/cad/brlcad/files/patch-src_other_stepcode_src_exp2cxx_complexSupport.h b/cad/brlcad/files/patch-src_other_stepcode_src_exp2cxx_complexSupport.h
new file mode 100644
index 000000000000..abed6c29701c
--- /dev/null
+++ b/cad/brlcad/files/patch-src_other_stepcode_src_exp2cxx_complexSupport.h
@@ -0,0 +1,26 @@
+--- src/other/stepcode/src/exp2cxx/complexSupport.h.orig	2020-03-12 15:32:37 UTC
++++ src/other/stepcode/src/exp2cxx/complexSupport.h
+@@ -162,19 +162,19 @@ class EntList {
+         // but all we need.
+         EntList * firstNot( JoinType );
+         EntList * nextNot( JoinType j ) {
+-            return next->firstNot( j );
++            return next == NULL ? NULL : next->firstNot( j );
+         }
+         EntList * firstWanted( MatchType );
+         EntList * nextWanted( MatchType mat ) {
+-            return next->firstWanted( mat );
++            return next == NULL ? NULL : next->firstWanted( mat );
+         }
+         EntList * lastNot( JoinType );
+         EntList * prevNot( JoinType j ) {
+-            return prev->lastNot( j );
++            return prev == NULL ? NULL : prev->lastNot( j );
+         }
+         EntList * lastWanted( MatchType );
+         EntList * prevWanted( MatchType mat ) {
+-            return prev->lastWanted( mat );
++            return prev == NULL ? NULL : prev->lastWanted( mat );
+         }
+ 
+         JoinType join;