diff --git a/lib/rspec/power_assert.rb b/lib/rspec/power_assert.rb
index 6963814..ea4ee17 100644
--- a/lib/rspec/power_assert.rb
+++ b/lib/rspec/power_assert.rb
@@ -1,6 +1,7 @@
 require "rspec/power_assert/version"
 require "rspec/core"
 require "power_assert"
+require "securerandom"
 
 module PowerAssert
   class << self
@@ -52,9 +53,17 @@ def is_asserted_by(&blk)
 
     private
 
+    def change_context(&blk)
+      self_name = :"_#{SecureRandom.hex}"
+      blk_name = :"_#{SecureRandom.hex}"
+      bind = blk.binding
+      bind.local_variable_set(self_name, self)
+      bind.local_variable_set(blk_name, blk)
+      bind.eval("-> { #{self_name}.instance_exec(&#{blk_name}) }")
+    end
+
     def evaluate_example(method_name, &blk)
-      # hack for context changing
-      pr = -> { self.instance_exec(&blk) }
+      pr = change_context(&blk)
 
       result, msg = ::PowerAssert.rspec_start(pr, assertion_method: method_name) do |tp|
         [tp.yield, tp.message_proc.call]