diff --git a/src/parsing/Line.php b/src/parsing/Line.php
index 135441c..1ac4468 100644
--- a/src/parsing/Line.php
+++ b/src/parsing/Line.php
@@ -489,10 +489,10 @@ public function concat($line, $dColumn, $mSources, $mNames)
             $generated->column += $dColumn;
             $fi = $source->fileIndex;
             $ni = $source->nameIndex;
-            if ((isset($mSources[$fi])) && ($fi !== null)) {
+            if (($fi !== null) && (isset($mSources[$fi]))) {
                 $source->fileIndex = $mSources[$fi];
             }
-            if ((isset($mNames[$ni])) && ($ni !== null)) {
+            if (($ni !== null) && (isset($mNames[$ni]))) {
                 $source->nameIndex = $mNames[$ni];
             }
             $npos[$generated->column] = $position;