diff --git a/spec/addressable/uri_spec.rb b/spec/addressable/uri_spec.rb
index 9ab8038e..0d7262fd 100644
--- a/spec/addressable/uri_spec.rb
+++ b/spec/addressable/uri_spec.rb
@@ -1061,7 +1061,9 @@ def to_s
   end
 
   it "should not allow destructive operations" do
-    expect { @uri.normalize! }.to raise_error(FrozenError)
+    below_2_5 = Gem::Version.new(RUBY_VERSION) < Gem::Version.new("2.5.0")
+    error = below_2_5 ? RuntimeError : FrozenError
+    expect { @uri.normalize! }.to raise_error(error)
   end
 end