diff --git a/src/Psalm/Internal/Analyzer/Statements/Expression/Fetch/VariableFetchAnalyzer.php b/src/Psalm/Internal/Analyzer/Statements/Expression/Fetch/VariableFetchAnalyzer.php
index aad5caa9962..fa3f70a841a 100644
--- a/src/Psalm/Internal/Analyzer/Statements/Expression/Fetch/VariableFetchAnalyzer.php
+++ b/src/Psalm/Internal/Analyzer/Statements/Expression/Fetch/VariableFetchAnalyzer.php
@@ -612,7 +612,10 @@ private static function getGlobalTypeInner(string $var_id, bool $files_full_path
         }
 
         if ($var_id === '$http_response_header') {
-            return Type::getNonEmptyList(Type::getNonFalsyString());
+            $list = Type::getNonEmptyList(Type::getNonFalsyString());
+            // $http_response_header exists only in the local scope after a successful network request
+            $list->possibly_undefined = true;
+            return $list;
         }
 
         if ($var_id === '$GLOBALS') {