diff --git a/ext/date/date_core.c b/ext/date/date_core.c
index e372a12cd7..d1d03fe407 100644
--- a/ext/date/date_core.c
+++ b/ext/date/date_core.c
@@ -4342,6 +4342,8 @@ get_limit(VALUE opt)
 static void
 check_limit(VALUE str, VALUE opt)
 {
+    if (NIL_P(str)) return;
+
     StringValue(str);
     size_t slen = RSTRING_LEN(str);
     size_t limit = get_limit(opt);
diff --git a/test/date/test_date_parse.rb b/test/date/test_date_parse.rb
index a486451ece..1217ee8be6 100644
--- a/test/date/test_date_parse.rb
+++ b/test/date/test_date_parse.rb
@@ -848,6 +848,9 @@ class TestDateParse < Test::Unit::TestCase
 
     h = Date._iso8601('')
     assert_equal({}, h)
+
+    h = Date._iso8601(nil)
+    assert_equal({}, h)
   end
 
   def test__rfc3339
@@ -863,6 +866,9 @@ class TestDateParse < Test::Unit::TestCase
 
     h = Date._rfc3339('')
     assert_equal({}, h)
+
+    h = Date._rfc3339(nil)
+    assert_equal({}, h)
   end
 
   def test__xmlschema
@@ -945,6 +951,9 @@ class TestDateParse < Test::Unit::TestCase
 
     h = Date._xmlschema('')
     assert_equal({}, h)
+
+    h = Date._xmlschema(nil)
+    assert_equal({}, h)
   end
 
   def test__rfc2822
@@ -977,6 +986,9 @@ class TestDateParse < Test::Unit::TestCase
 
     h = Date._rfc2822('')
     assert_equal({}, h)
+
+    h = Date._rfc2822(nil)
+    assert_equal({}, h)
   end
 
   def test__httpdate
@@ -997,6 +1009,9 @@ class TestDateParse < Test::Unit::TestCase
 
     h = Date._httpdate('')
     assert_equal({}, h)
+
+    h = Date._httpdate(nil)
+    assert_equal({}, h)
   end
 
   def test__jisx0301
@@ -1073,6 +1088,9 @@ class TestDateParse < Test::Unit::TestCase
 
     h = Date._jisx0301('')
     assert_equal({}, h)
+
+    h = Date._jisx0301(nil)
+    assert_equal({}, h)
   end
 
   def test_iso8601