diff --git a/lib/typeprof/core/graph/vertex.rb b/lib/typeprof/core/graph/vertex.rb
index e2fa29ba..c0e726e7 100644
--- a/lib/typeprof/core/graph/vertex.rb
+++ b/lib/typeprof/core/graph/vertex.rb
@@ -23,7 +23,7 @@ def each_type(&blk)
     def check_match(genv, changes, vtx)
       vtx.each_type do |ty|
         if ty.is_a?(Type::Var)
-          changes.add_edge(genv, self, ty.vtx)
+          changes.add_edge(genv, self, ty.vtx) if self != ty.vtx
           return true
         end
       end
diff --git a/scenario/regressions/self-type-var.rb b/scenario/regressions/self-type-var.rb
new file mode 100644
index 00000000..7c3e44c3
--- /dev/null
+++ b/scenario/regressions/self-type-var.rb
@@ -0,0 +1,6 @@
+## update: test.rb
+def check2
+  @ary = [].to_a
+  @ary = @ary.concat(@ary)
+  @ary = @ary.concat(@ary)
+end