diff --git a/PHPSkills/FactorGraphs/Factor.php b/PHPSkills/FactorGraphs/Factor.php
index ad571e3..427c517 100644
--- a/PHPSkills/FactorGraphs/Factor.php
+++ b/PHPSkills/FactorGraphs/Factor.php
@@ -49,8 +49,8 @@ abstract class Factor
     public function updateMessageIndex($messageIndex)
     {
         Guard::argumentIsValidIndex($messageIndex, count($this->_messages), "messageIndex");
-        $message = $this->_messages[$messageIndex];
-        $variable = $this->_messageToVariableBinding->getValue($this->_messages[$messageIndex]);
+        $message = &$this->_messages[$messageIndex];
+        $variable = &$this->_messageToVariableBinding->getValue($this->_messages[$messageIndex]);
         return $this->updateMessageVariable($message, $variable);
     }
 
diff --git a/PHPSkills/TrueSkill/Factors/GaussianGreaterThanFactor.php b/PHPSkills/TrueSkill/Factors/GaussianGreaterThanFactor.php
index ba9623b..073cefd 100644
--- a/PHPSkills/TrueSkill/Factors/GaussianGreaterThanFactor.php
+++ b/PHPSkills/TrueSkill/Factors/GaussianGreaterThanFactor.php
@@ -58,7 +58,7 @@ class GaussianGreaterThanFactor extends GaussianFactor
         $epsilsonTimesSqrtC = $this->_epsilon*$sqrtC;
         $d = $messageFromVar->getPrecisionMean();
 
-        $denom = 1.0 - TruncatedGaussianCorrectionFunctions::vExceedsMargin($dOnSqrtC, $epsilsonTimesSqrtC);
+        $denom = 1.0 - TruncatedGaussianCorrectionFunctions::wExceedsMargin($dOnSqrtC, $epsilsonTimesSqrtC);
 
         $newPrecision = $c/$denom;
         $newPrecisionMean = ($d +
diff --git a/PHPSkills/TrueSkill/Factors/GaussianWeightedSumFactor.php b/PHPSkills/TrueSkill/Factors/GaussianWeightedSumFactor.php
index d1f18e9..03a9729 100644
--- a/PHPSkills/TrueSkill/Factors/GaussianWeightedSumFactor.php
+++ b/PHPSkills/TrueSkill/Factors/GaussianWeightedSumFactor.php
@@ -218,8 +218,8 @@ class GaussianWeightedSumFactor extends GaussianFactor
         $allMessagesCount = count($allMessages);
         for ($i = 0; $i < $allMessagesCount; $i++)
         {
-            $updatedMessages[] =$allMessages[$indicesToUse[$i]];
-            $updatedVariables[] = $allVariables[$indicesToUse[$i]];
+            $updatedMessages[] = &$allMessages[$indicesToUse[$i]];
+            $updatedVariables[] = &$allVariables[$indicesToUse[$i]];
         }
 
         return $this->updateHelper($this->_weights[$messageIndex],