Index: tests/t3lib/t3lib_pagerenderer_testcase.php
===================================================================
--- tests/t3lib/t3lib_pagerenderer_testcase.php	(Revision 6571)
+++ tests/t3lib/t3lib_pagerenderer_testcase.php	(Arbeitskopie)
@@ -634,8 +634,22 @@
 			$out
 		);
 	}
-	
-  
 
+	/**
+	 * Tests whether labels are delivered in a non-UTF-8 context.
+	 * (background: json_encode() requires UTF-8 to work properly)
+	 *
+	 * @test
+	 */
+	public function isInlineLanguageLabelDeliveredWithNonUTF8() {
+		$testPrefix = uniqid('test');
+		$this->fixture->loadExtCore();
+		$this->fixture->setCharSet('iso-8859-1');
+		$this->fixture->addInlineLanguageLabel($testPrefix, $testPrefix . "_\xd8");
+
+		$out = $this->fixture->render();
+
+		$this->assertContains($testPrefix . '_\\u00d8', $out);
+	}
 }
 ?>
\ No newline at end of file
Index: t3lib/class.t3lib_pagerenderer.php
===================================================================
--- t3lib/class.t3lib_pagerenderer.php	(Revision 6571)
+++ t3lib/class.t3lib_pagerenderer.php	(Arbeitskopie)
@@ -128,6 +128,7 @@
 	public function __construct($templateFile = '', $backPath = NULL) {
 
 		$this->reset();
+		$this->csConvObj = t3lib_div::makeInstance('t3lib_cs');
 
 		if (strlen($templateFile)) {
 			$this->templateFile = $templateFile;
@@ -1193,6 +1194,16 @@
 			);
 		}
 
+			// Convert labels/settings back to UTF-8 since json_encode() only works with UTF-8:
+		if ($this->getCharSet() !== 'utf-8') {
+			if ($this->inlineLanguageLabels) {
+				$this->csConvObj->convArray($this->inlineLanguageLabels, $this->getCharSet(), 'utf-8');
+			}
+			if ($this->inlineSettings) {
+				$this->csConvObj->convArray($this->inlineSettings, $this->getCharSet(), 'utf-8');
+			}
+		}
+
 		$inlineSettings = $this->inlineLanguageLabels ? 'TYPO3.lang = ' . json_encode($this->inlineLanguageLabels) . ';' : '';
 		$inlineSettings .= $this->inlineSettings ? 'TYPO3.settings = ' . json_encode($this->inlineSettings) . ';' : '';