diff --git a/lib/forecast.io.php b/lib/forecast.io.php
index 34116d6..086a957 100644
--- a/lib/forecast.io.php
+++ b/lib/forecast.io.php
@@ -91,7 +91,7 @@ function getHistoricalConditions($latitude, $longitude, $units = 'auto', $timest
 
     $exclusions = 'currently,minutely,hourly,alerts,flags';
 
-    $data = $this->requestData($latitude, $longitude, $units $timestamp, $exclusions);
+    $data = $this->requestData($latitude, $longitude, $units, $timestamp, $exclusions);
 
     if ($data !== false) {
 
@@ -418,4 +418,4 @@ function getSunset($format=null) {
   }
   
 }
-?>
\ No newline at end of file
+?>