diff --git a/Mesh/yamakawa.cpp b/Mesh/yamakawa.cpp
index 5dc99e5736f242fefde5faefc02350c5d5237d93..89985b40f75aecd88b2aac858fd413fa9c7c6be9 100755
--- a/Mesh/yamakawa.cpp
+++ b/Mesh/yamakawa.cpp
@@ -960,6 +960,9 @@ void Recombinator::modify_surfaces(MVertex* a,MVertex* b,MVertex* c,MVertex* d){
   std::multiset<Tuple>::iterator it1;
   std::multiset<Tuple>::iterator it2;
 
+  gf1 = NULL;
+  gf2 = NULL;
+
   tuple1 = Tuple(a,b,c);
   tuple2 = Tuple(c,d,a);	
   
@@ -2583,6 +2586,9 @@ void Supplementary::modify_surfaces(MVertex* a,MVertex* b,MVertex* c,MVertex* d)
   std::multiset<Tuple>::iterator it1;
   std::multiset<Tuple>::iterator it2;
 	
+  gf1 = NULL;
+  gf2 = NULL;	
+	
   tuple1 = Tuple(a,b,c);
   tuple2 = Tuple(c,d,a);	
 	
@@ -3991,6 +3997,9 @@ void PostOp::modify_surfaces(MVertex* a,MVertex* b,MVertex* c,MVertex* d){
   std::multiset<Tuple>::iterator it1;
   std::multiset<Tuple>::iterator it2;
 	
+  gf1 = NULL;
+  gf2 = NULL;	
+	
   tuple1 = Tuple(a,b,c);
   tuple2 = Tuple(c,d,a);