diff --git a/nexus/Install/Install.php b/nexus/Install/Install.php
index bf5d1e66..8250a473 100644
--- a/nexus/Install/Install.php
+++ b/nexus/Install/Install.php
@@ -172,8 +172,8 @@ class Install
                 $output = [];
                 $command = "php -r 'var_export(function_exists(\"$fn\"));'";
                 $result = exec($command, $output, $result_code);
-                $lastThreeChars = substr(trim($output[0]), -3);
-                $exists = $lastThreeChars == 'true';
+                $lastFourChars = substr(trim($output[0]), -4);
+                $exists = $lastFourChars == 'true';
                 if (!$exists) {
                     $disabledFunctions[] = $fn;
                 }