diff --git a/lib/extism/plugin.rb b/lib/extism/plugin.rb
index 6158e1a..45edf61 100644
--- a/lib/extism/plugin.rb
+++ b/lib/extism/plugin.rb
@@ -47,7 +47,7 @@ def initialize(wasm, environment: nil, functions: [], wasi: false, config: nil)
       end
       $PLUGINS[object_id] = { plugin: @plugin }
       ObjectSpace.define_finalizer(self, $FREE_PLUGIN)
-      return unless !config.nil? and @plugin.null?
+      return if config.nil? or @plugin.null?
 
       s = JSON.generate(config)
       ptr = FFI::MemoryPointer.from_string(s)
diff --git a/test/test_extism.rb b/test/test_extism.rb
index 3b3d130..d18e221 100644
--- a/test/test_extism.rb
+++ b/test/test_extism.rb
@@ -64,7 +64,7 @@ def test_that_it_has_a_version_number
   end
 
   def test_plugin_call
-    plugin = Extism::Plugin.new(vowels_manifest)
+    plugin = Extism::Plugin.new(vowels_manifest, config: { vowels: 'aeiouyAEIOUY' })
     res = JSON.parse(plugin.call('count_vowels', 'this is a test'))
     assert_equal res['count'], 4
     res = JSON.parse(plugin.call('count_vowels', 'this is a test again'))
@@ -73,6 +73,9 @@ def test_plugin_call
     assert_equal res['count'], 6
     res = JSON.parse(plugin.call('count_vowels', '🌎hello🌎world🌎'))
     assert_equal res['count'], 3
+    res = JSON.parse(plugin.call('count_vowels', 'does y count?'))
+    assert_equal res['count'], 5
+    assert_equal res['vowels'], 'aeiouyAEIOUY'
   end
 
   def test_can_free_plugin