diff --git a/source/FluidXml/FluidInsertionHandler.php b/source/FluidXml/FluidInsertionHandler.php
index f47fd46..1c0e695 100644
--- a/source/FluidXml/FluidInsertionHandler.php
+++ b/source/FluidXml/FluidInsertionHandler.php
@@ -226,6 +226,11 @@ protected function attachNodes($parent, $nodes, $fn): array
                 $context = [];
 
                 foreach ($nodes as $el) {
+                        // DOMDocumentType cannot be imported as a child node.
+                        if ($el instanceof \DOMDocumentType) {
+                                continue;
+                        }
+
                         $el        = $this->dom->importNode($el, true);
                         $context[] = $fn($parent, $el);
                 }
diff --git a/specs/FluidXml.php b/specs/FluidXml.php
index 6cac1ef..5132f19 100644
--- a/specs/FluidXml.php
+++ b/specs/FluidXml.php
@@ -142,6 +142,34 @@
 
                         assert_is_a($actual, \Exception::class);
                 });
+
+                it('should import an XML file containing a DOCTYPE declaration', function () {
+                        $file = "{$this->out_dir}.test_load_doctype.xml";
+                        $doc  = "<?xml version=\"1.0\" encoding=\"UTF-8\"?>\n"
+                              . "<!DOCTYPE fcpxml>\n"
+                              . "<fcpxml version=\"1.8\"><resources/></fcpxml>";
+
+                        \file_put_contents($file, $doc);
+                        $xml = FluidXml::load($file);
+                        \unlink($file);
+
+                        $expected = "<fcpxml version=\"1.8\">\n  <resources/>\n</fcpxml>";
+                        assert_equal_xml($xml, $expected);
+                });
+        });
+
+        describe('.addChild() with DOCTYPE', function () {
+                it('should not throw when adding an XML string with a DOCTYPE declaration', function () {
+                        $xml    = new FluidXml(null);
+                        $xmlStr = "<?xml version=\"1.0\" encoding=\"UTF-8\"?>\n"
+                                . "<!DOCTYPE fcpxml>\n"
+                                . "<fcpxml version=\"1.8\"><resources/></fcpxml>";
+
+                        $xml->addChild($xmlStr);
+
+                        $expected = "<fcpxml version=\"1.8\">\n  <resources/>\n</fcpxml>";
+                        assert_equal_xml($xml, $expected);
+                });
         });
 
         if (\version_compare(\phpversion(), '7', '>=')) {