diff --git a/lib/typeprof/core/ast/call.rb b/lib/typeprof/core/ast/call.rb
index a2ddb1e3..59f9c931 100644
--- a/lib/typeprof/core/ast/call.rb
+++ b/lib/typeprof/core/ast/call.rb
@@ -247,7 +247,7 @@ def modified_vars(tbl, vars)
               subnode.modified_vars(tbl, vars)
             end
           else
-            subnode.each {|n| n.modified_vars(tbl, vars) }
+            subnode.each {|n| n&.modified_vars(tbl, vars) }
           end
         end
       end
diff --git a/scenario/args/anonymous_rest.rb b/scenario/args/anonymous_rest.rb
index e66e7efb..deebf1ee 100644
--- a/scenario/args/anonymous_rest.rb
+++ b/scenario/args/anonymous_rest.rb
@@ -7,10 +7,17 @@ def bar(*)
   nil
 end
 
+def foo_in_if(*)
+  if true
+    bar(*)
+  end
+end
+
 bar(1, "foo")
 
 ## assert
 class Object
   def foo: (*untyped) -> nil
   def bar: (*Integer | String) -> nil
+  def foo_in_if: (*untyped) -> nil
 end