diff --git a/Library/Optimizers/FunctionCall/GlobalsSetOptimizer.php b/Library/Optimizers/FunctionCall/GlobalsSetOptimizer.php
index e1e99a375..457c70125 100644
--- a/Library/Optimizers/FunctionCall/GlobalsSetOptimizer.php
+++ b/Library/Optimizers/FunctionCall/GlobalsSetOptimizer.php
@@ -128,7 +128,7 @@ private function resolveInternalValue(array $definition, array $expression, stri
             case 'char':
             case 'uchar':
                 return strtr(
-                    '(Z_TYPE_P(:v) == IS_STRING ? (Z_STRLEN_P(:v) ? zval_get_string(:v)[0] : NULL) : zval_get_long(:v))',
+                    '(Z_TYPE_P(:v) == IS_STRING ? (Z_STRLEN_P(:v) ? Z_STRVAL_P(:v)[0] : NULL) : zval_get_long(:v))',
                     [':v' => $value]
                 );
             case 'double':