diff --git a/test/ruby/test_m17n_comb.rb b/test/ruby/test_m17n_comb.rb
index b275d78356..903e0de134 100644
--- a/test/ruby/test_m17n_comb.rb
+++ b/test/ruby/test_m17n_comb.rb
@@ -722,14 +722,14 @@ class TestM17NComb < Test::Unit::TestCase
   def test_str_crypt
     begin
       # glibc 2.16 or later denies salt contained other than [0-9A-Za-z./] #7312
-      glibcver = `/lib/libc.so.6`[/\AGNU C Library.*version ([0-9.]+)/, 1].split('.')
+      glibcver = `/lib/libc.so.6`[/\AGNU C Library.*version ([0-9.]+)/, 1].split('.').map(&:to_i)
       strict_crypt = (glibcver <=> [2, 16]) > -1
     rescue
     end
 
     combination(STRINGS, STRINGS) {|str, salt|
       if strict_crypt
-        next unless /\A[0-9a-zA-Z.\/]+\z/ =~ salt
+        next unless salt.ascii_only? && /\A[0-9a-zA-Z.\/]+\z/ =~ salt
       end
       if a(salt).length < 2
         assert_raise(ArgumentError) { str.crypt(salt) }