diff --git a/src/nusoap.php b/src/nusoap.php
index 3e9a60c..9fadfe3 100755
--- a/src/nusoap.php
+++ b/src/nusoap.php
@@ -7691,7 +7691,7 @@ function call($operation, $params = array(), $namespace = 'http://tempuri.org',
             // serialize
             $payload = '';
 
-            if ($use = 'literal wrapped') {
+            if ($use == 'literal wrapped') {
                 // 'literal wrapped' is only sensible (and defined) for 'document'.
                 if ($style == 'document') {
                     $usewrapped = true;