diff --git a/compile.c b/compile.c
index c270308acc..ca998bef15 100644
--- a/compile.c
+++ b/compile.c
@@ -1939,6 +1939,7 @@ iseq_set_sequence(rb_iseq_t *iseq, LINK_ANCHOR *const anchor)
     iseq->body->is_entries = ZALLOC_N(union iseq_inline_storage_entry, iseq->body->is_size);
     iseq->body->ci_entries = (struct rb_call_info *)ruby_xmalloc(sizeof(struct rb_call_info) * iseq->body->ci_size +
 								 sizeof(struct rb_call_info_with_kwarg) * iseq->body->ci_kw_size);
+    MEMZERO(iseq->body->ci_entries + iseq->body->ci_size, struct rb_call_info_with_kwarg,  iseq->body->ci_kw_size); /* need to clear ci_kw entries */
     iseq->body->cc_entries = ZALLOC_N(struct rb_call_cache, iseq->body->ci_size + iseq->body->ci_kw_size);
 
     ISEQ_COMPILE_DATA(iseq)->ci_index = ISEQ_COMPILE_DATA(iseq)->ci_kw_index = 0;
diff --git a/test/ruby/test_optimization.rb b/test/ruby/test_optimization.rb
index 40015c57dd..3ea867e8e1 100644
--- a/test/ruby/test_optimization.rb
+++ b/test/ruby/test_optimization.rb
@@ -647,4 +647,19 @@ class TestRubyOptimization < Test::Unit::TestCase
       eval "def foo; 1.times{|(a), &b| nil && a}; end"
     END
   end
+
+  def test_clear_unreachable_keyword_args
+    assert_separately [], <<-END
+      script =  <<-EOS
+        if true
+        else
+          foo(k1:1)
+        end
+      EOS
+      GC.stress = true
+      30.times{
+        RubyVM::InstructionSequence.compile(script)
+      }
+    END
+  end
 end