diff --git a/src/Negotiation/Negotiator.php b/src/Negotiation/Negotiator.php
index 40f10c4..02215ee 100644
--- a/src/Negotiation/Negotiator.php
+++ b/src/Negotiation/Negotiator.php
@@ -157,6 +157,10 @@ protected function parseParameters($value)
         foreach ($parts as $part) {
             $part = explode('=', $part);
 
+            if (2 !== count($part)) {
+                continue;
+            }
+
             if ('q' !== $key = strtolower($part[0])) {
                 $parameters[$key] = $part[1];
             }
diff --git a/tests/Negotiation/Tests/NegotiatorTest.php b/tests/Negotiation/Tests/NegotiatorTest.php
index f859dca..27f26a6 100644
--- a/tests/Negotiation/Tests/NegotiatorTest.php
+++ b/tests/Negotiation/Tests/NegotiatorTest.php
@@ -274,6 +274,10 @@ public static function dataProviderForParseParameters()
                 'application/json;q=1.0',
                 array(),
             ),
+            array(
+                'application/json;foo',
+                array(),
+            ),
         );
     }
 }