diff --git a/includes/engines/LuaCommon/LuaEngine.php b/includes/engines/LuaCommon/LuaEngine.php
index 969c6b8b..5f136864 100644
--- a/includes/engines/LuaCommon/LuaEngine.php
+++ b/includes/engines/LuaCommon/LuaEngine.php
@@ -874,6 +874,9 @@ abstract class Scribunto_LuaEngine extends ScribuntoEngineBase {
 	 * @param string $text wikitext
 	 */
 	public function addWarning( $text ) {
+		$args = func_get_args();
+		$this->checkString( 'addWarning', $args, 0 );
+
 		$this->getParser()->getOutput()->addWarning( $text );
 	}
 
diff --git a/tests/phpunit/engines/LuaCommon/CommonTests.lua b/tests/phpunit/engines/LuaCommon/CommonTests.lua
index fef18edf..80fd5f85 100644
--- a/tests/phpunit/engines/LuaCommon/CommonTests.lua
+++ b/tests/phpunit/engines/LuaCommon/CommonTests.lua
@@ -384,4 +384,13 @@ return testframework.getTestProvider( {
 	  func = test.loadData.rawset,
 	  expect = { 'ugh', 'foo bar', 'foo bar' },
 	},
+
+	{ name = 'mw.addWarning',
+	  func = mw.addWarning, args = { 'warn' },
+	  expect = {},
+	},
+	{ name = 'mw.addWarning, bad type',
+	  func = mw.addWarning, args = { true },
+	  expect = "bad argument #1 to 'addWarning' (string expected)",
+	},
 } )
diff --git a/tests/phpunit/engines/LuaCommon/LuaCommonTest.php b/tests/phpunit/engines/LuaCommon/LuaCommonTest.php
index eac72fda..e8be6108 100644
--- a/tests/phpunit/engines/LuaCommon/LuaCommonTest.php
+++ b/tests/phpunit/engines/LuaCommon/LuaCommonTest.php
@@ -828,4 +828,27 @@ class Scribunto_LuaCommonTest extends Scribunto_LuaEngineTestBase {
 		$text = $parser->mStripState->unstripBoth( $text );
 		$this->assertSame( '>false<', $text );
 	}
+
+	public function testAddWarning() {
+		$engine = $this->getEngine();
+		$parser = $engine->getParser();
+		$pp = $parser->getPreprocessor();
+
+		$this->extraModules['Module:TestAddWarning'] = '
+			local p = {}
+
+			p.foo = function ()
+				mw.addWarning( "Don\'t panic!" )
+				return "ok"
+			end
+
+			return p
+		';
+
+		$frame = $pp->newFrame();
+		$text = $frame->expand( $pp->preprocessToObj( ">{{#invoke:TestAddWarning|foo}}<" ) );
+		$text = $parser->mStripState->unstripBoth( $text );
+		$this->assertSame( '>ok<', $text );
+		$this->assertSame( [ 'Don\'t panic!' ], $parser->getOutput()->getWarnings() );
+	}
 }