diff --git a/enum.c b/enum.c
index 2b2806a6c8..086e3aa13c 100644
--- a/enum.c
+++ b/enum.c
@@ -2840,18 +2840,19 @@ cycle_i(RB_BLOCK_CALL_FUNC_ARGLIST(i, ary))
 static VALUE
 enum_cycle_size(VALUE self, VALUE args, VALUE eobj)
 {
-    long mul;
+    long mul = 0;
     VALUE n = Qnil;
-    VALUE size = enum_size(self, args, 0);
-
-    if (size == Qnil) return Qnil;
-    if (FIXNUM_ZERO_P(size)) return size;
+    VALUE size;
 
     if (args && (RARRAY_LEN(args) > 0)) {
 	n = RARRAY_AREF(args, 0);
+	if (!NIL_P(n)) mul = NUM2LONG(n);
     }
-    if (n == Qnil) return DBL2NUM(INFINITY);
-    mul = NUM2LONG(n);
+
+    size = enum_size(self, args, 0);
+    if (NIL_P(size) || FIXNUM_ZERO_P(size)) return size;
+
+    if (NIL_P(n)) return DBL2NUM(INFINITY);
     if (mul <= 0) return INT2FIX(0);
     n = LONG2FIX(mul);
     return rb_funcallv(size, '*', 1, &n);
diff --git a/test/ruby/test_enumerator.rb b/test/ruby/test_enumerator.rb
index 0ee11dad36..51f69be37d 100644
--- a/test/ruby/test_enumerator.rb
+++ b/test/ruby/test_enumerator.rb
@@ -590,6 +590,8 @@ class TestEnumerator < Test::Unit::TestCase
     assert_equal 126, @sized.cycle(3).size
     assert_equal Float::INFINITY, [].to_enum { 42 }.cycle.size
     assert_equal 0, [].to_enum { 0 }.cycle.size
+
+    assert_raise(TypeError) {[].to_enum { 0 }.cycle("").size}
   end
 
   def test_size_for_loops
diff --git a/test/ruby/test_lazy_enumerator.rb b/test/ruby/test_lazy_enumerator.rb
index 4db58e7619..56890f4b6e 100644
--- a/test/ruby/test_lazy_enumerator.rb
+++ b/test/ruby/test_lazy_enumerator.rb
@@ -507,7 +507,9 @@ EOS
       def size; 0; end
       include Enumerable
     end
-    assert_equal 0, obj.lazy.cycle.size
+    lazy = obj.lazy
+    assert_equal 0, lazy.cycle.size
+    assert_raise(TypeError) {lazy.cycle("").size}
   end
 
   def test_map_zip