diff --git a/Parser/Handler/StringHandler.php b/Parser/Handler/StringHandler.php
index 9869176..72e94c3 100644
--- a/Parser/Handler/StringHandler.php
+++ b/Parser/Handler/StringHandler.php
@@ -55,7 +55,7 @@ public function handle(Reader $reader, TokenStream $stream)
         $match = $reader->findPattern($this->patterns->getQuotedStringPattern($quote));
 
         if (!$match) {
-            throw new InternalErrorException(sprintf('Should have found at least an empty match at %s.', $reader->getPosition()));
+            throw new InternalErrorException(sprintf('Should have found at least an empty match at %d.', $reader->getPosition()));
         }
 
         // check unclosed strings
diff --git a/XPath/Extension/FunctionExtension.php b/XPath/Extension/FunctionExtension.php
index 103b6a5..a121ab8 100644
--- a/XPath/Extension/FunctionExtension.php
+++ b/XPath/Extension/FunctionExtension.php
@@ -58,7 +58,7 @@ public function translateNthChild(XPathExpr $xpath, FunctionNode $function, $las
         try {
             list($a, $b) = Parser::parseSeries($function->getArguments());
         } catch (SyntaxErrorException $e) {
-            throw new ExpressionErrorException(sprintf('Invalid series: %s.', implode(', ', $function->getArguments())), 0, $e);
+            throw new ExpressionErrorException(sprintf('Invalid series: "%s".', implode('", "', $function->getArguments())), 0, $e);
         }
 
         $xpath->addStarPrefix();