diff --git a/lib/puppet/parser/functions/is_domain_name.rb b/lib/puppet/parser/functions/is_domain_name.rb
index b3fee965a..24cc2085f 100644
--- a/lib/puppet/parser/functions/is_domain_name.rb
+++ b/lib/puppet/parser/functions/is_domain_name.rb
@@ -13,7 +13,7 @@ module Puppet::Parser::Functions
         "given #{arguments.size} for 1")
     end
 
-    domain = arguments[0]
+    domain = arguments[0].dup
 
     # Limits (rfc1035, 3.1)
     domain_max_length=255
diff --git a/spec/functions/is_domain_name_spec.rb b/spec/functions/is_domain_name_spec.rb
index 4d05f5cdc..5ab8369c0 100755
--- a/spec/functions/is_domain_name_spec.rb
+++ b/spec/functions/is_domain_name_spec.rb
@@ -61,4 +61,11 @@
     result = scope.function_is_domain_name(["not valid"])
     expect(result).to(be_falsey)
   end
+
+  # Values obtained from Facter values will be frozen strings
+  # in newer versions of Facter:
+  it "should not throw an exception if passed a frozen string" do
+    result = scope.function_is_domain_name(["my.domain.name".freeze])
+    expect(result).to(be_truthy)
+  end
 end