diff --git a/src/PhpWord/Writer/RTF/Part/Header.php b/src/PhpWord/Writer/RTF/Part/Header.php
index 97644fe4ac..9399b8be0b 100644
--- a/src/PhpWord/Writer/RTF/Part/Header.php
+++ b/src/PhpWord/Writer/RTF/Part/Header.php
@@ -201,9 +201,17 @@ private function registerFont(): void
             $elements = $section->getElements();
             $this->registerBorderColor($section->getStyle());
             foreach ($elements as $element) {
-                if (method_exists($element, 'getFontStyle')) {
+                if (is_object($element) && method_exists($element, 'getFontStyle')) {
                     $style = $element->getFontStyle();
                     $this->registerFontItems($style);
+                } elseif (is_object($element) && method_exists($element, 'getElements')) {
+                    $subElements = $element->getElements();
+                    foreach ($subElements as $subElement) {
+                        if (is_object($subElement) && method_exists($subElement, 'getFontStyle')) {
+                            $style = $subElement->getFontStyle();
+                            $this->registerFontItems($style);
+                        }
+                    }
                 }
             }
         }