diff --git a/lib/irb/ext/eval_history.rb b/lib/irb/ext/eval_history.rb
index 6c21ff00e..fa4a95a92 100644
--- a/lib/irb/ext/eval_history.rb
+++ b/lib/irb/ext/eval_history.rb
@@ -50,7 +50,7 @@ def eval_history=(no)
           @eval_history_values = EvalHistory.new(no)
           IRB.conf[:__TMP__EHV__] = @eval_history_values
           workspace.evaluate("__ = IRB.conf[:__TMP__EHV__]")
-          IRB.conf.delete(:__TMP_EHV__)
+          IRB.conf.delete(:__TMP__EHV__)
         end
       else
         @eval_history_values = nil