diff --git a/controllers/PortableInfoboxParserTagController.class.php b/controllers/PortableInfoboxParserTagController.class.php
index 75651f0..df84855 100644
--- a/controllers/PortableInfoboxParserTagController.class.php
+++ b/controllers/PortableInfoboxParserTagController.class.php
@@ -102,10 +102,12 @@ class PortableInfoboxParserTagController extends WikiaController {
 
 	private function getThemeWithDefault( $params, PPFrame $frame ) {
 		$value = isset( $params[ 'theme-source' ] ) ? $frame->getArgument( $params[ 'theme-source' ] ) : false;
-		return self::INFOBOX_THEME_PREFIX . $this->getThemePrefix( $params, $value );
+		$themeName = $this->getThemeName( $params, $value );
+		//make sure no whitespaces, prevents side effects
+		return self::INFOBOX_THEME_PREFIX . preg_replace( '|\s+|s', '-', $themeName );
 	}
 
-	private function getThemePrefix( $params, $value ) {
+	private function getThemeName( $params, $value ) {
 		return !empty( $value ) ? $value :
 			// default logic
 			( isset( $params[ 'theme' ] ) ? $params[ 'theme' ] : self::DEFAULT_THEME_NAME );
diff --git a/tests/PortableInfoboxParserTagControllerTest.php b/tests/PortableInfoboxParserTagControllerTest.php
index 7cd276c..9fb8f96 100644
--- a/tests/PortableInfoboxParserTagControllerTest.php
+++ b/tests/PortableInfoboxParserTagControllerTest.php
@@ -94,4 +94,34 @@ class PortableInfoboxParserTagControllerTest extends WikiaBaseTest {
 			PortableInfoboxParserTagController::INFOBOX_THEME_PREFIX . PortableInfoboxParserTagController::DEFAULT_THEME_NAME
 		) );
 	}
+
+	public function testWhiteSpacedThemeInfobox() {
+		$text = '<data><default>test</default></data>';
+		$defaultTheme = 'test test';
+		$expectedName = 'test-test';
+
+		$marker = $this->controller->renderInfobox( $text, [ 'theme' => $defaultTheme ], $this->parser,
+			$this->parser->getPreprocessor()->newFrame() )[ 0 ];
+		$output = $this->controller->replaceMarkers( $marker );
+
+		$this->assertTrue( $this->checkClassName(
+			$output,
+			PortableInfoboxParserTagController::INFOBOX_THEME_PREFIX . $expectedName
+		) );
+	}
+
+	public function testMultiWhiteSpacedThemeInfobox() {
+		$text = '<data><default>test</default></data>';
+		$defaultTheme = "test    test\n test\ttest";
+		$expectedName = 'test-test-test-test';
+
+		$marker = $this->controller->renderInfobox( $text, [ 'theme' => $defaultTheme ], $this->parser,
+			$this->parser->getPreprocessor()->newFrame() )[ 0 ];
+		$output = $this->controller->replaceMarkers( $marker );
+
+		$this->assertTrue( $this->checkClassName(
+			$output,
+			PortableInfoboxParserTagController::INFOBOX_THEME_PREFIX . $expectedName
+		) );
+	}
 }