diff --git a/regexec.c b/regexec.c
index 4b02e7f9b5..8638013618 100644
--- a/regexec.c
+++ b/regexec.c
@@ -542,7 +542,7 @@ init_cache_opcodes(const regex_t* reg, OnigCacheOpcode* cache_opcodes, long* num
     cache_opcodes->num_cache_points_at_outer_repeat = num_cache_points_at_repeat;\
     cache_opcodes->num_cache_points_in_outer_repeat = 0;\
     cache_opcodes->lookaround_nesting = lookaround_nesting;\
-    cache_point += lookaround_nesting > 0 ? 2 : 1;\
+    cache_point += lookaround_nesting != 0 ? 2 : 1;\
     cache_opcodes++;\
   } while (0)
 
diff --git a/test/ruby/test_regexp.rb b/test/ruby/test_regexp.rb
index d4aae16037..b889b1a64e 100644
--- a/test/ruby/test_regexp.rb
+++ b/test/ruby/test_regexp.rb
@@ -1979,6 +1979,14 @@ class TestRegexp < Test::Unit::TestCase
     end
   end
 
+  def test_bug_20083 # [Bug #20083]
+    re = /([\s]*ABC)$/i
+    (1..100).each do |n|
+      text = "#{"0" * n}ABC"
+      assert text.match?(re)
+    end
+  end
+
   def test_linear_time_p
     assert_send [Regexp, :linear_time?, /a/]
     assert_send [Regexp, :linear_time?, 'a']