Per the spec, missing partials should be treated as an empty string.

src/Mustache/Compiler.php

@@ -221,7 +221,11 @@ class Mustache_Compiler {
 		return sprintf($this->prepare(self::INVERTED_SECTION, $level), $id, $method, $id, $this->walk($nodes, $level));
 	}
 
-	const PARTIAL = '$buffer .= $this->mustache->loadPartial(%s)->renderInternal($context, %s);';
+	const PARTIAL = '
+		if ($partial = $this->mustache->loadPartial(%s)) {
+			$buffer .= $partial->renderInternal($context, %s);
+		}
+	';
 
 	/**
 	 * Generate Mustache Template partial call PHP source.

src/Mustache/Mustache.php

@@ -414,7 +414,11 @@ class Mustache_Mustache {
 	 * @return Mustache_Template
 	 */
 	public function loadPartial($name) {
-		return $this->loadSource($this->getPartialsLoader()->load($name));
+		try {
+			return $this->loadSource($this->getPartialsLoader()->load($name));
+		} catch (InvalidArgumentException $e) {
+			// If the named partial cannot be found, return null.
+		}
 	}
 
 	/**

test/Mustache/Test/MustacheTest.php

@@ -146,6 +146,17 @@ class Mustache_Test_MustacheTest extends PHPUnit_Framework_TestCase {
 		$mustache->setPartials(array('foo' => '{{ foo }}'));
 	}
 
+	public function testMissingPartialsTreatedAsEmptyString() {
+		$mustache = new Mustache_Mustache(array(
+			'partials_loader' => new Mustache_Loader_ArrayLoader(array(
+				'foo' => 'FOO',
+				'baz' => 'BAZ',
+			))
+		));
+
+		$this->assertEquals('FOOBAZ', $mustache->render('{{>foo}}{{>bar}}{{>baz}}', array()));
+	}
+
 	public function testHelpers() {
 		$foo = function() { return 'foo'; };
 		$bar = 'BAR';