diff --git a/openmc/geometry.py b/openmc/geometry.py
index 60f4a390d44..8815f2c8380 100644
--- a/openmc/geometry.py
+++ b/openmc/geometry.py
@@ -293,7 +293,8 @@ def from_xml(
         if isinstance(materials, (str, os.PathLike)):
             materials = openmc.Materials.from_xml(materials)
 
-        tree = ET.parse(path)
+        parser = ET.XMLParser(huge_tree=True)
+        tree = ET.parse(path, parser=parser)
         root = tree.getroot()
 
         return cls.from_xml_element(root, materials)
diff --git a/openmc/material.py b/openmc/material.py
index 1f5496f15ea..d42c489aee0 100644
--- a/openmc/material.py
+++ b/openmc/material.py
@@ -1754,7 +1754,8 @@ def from_xml(cls, path: PathLike = 'materials.xml') -> Materials:
             Materials collection
 
         """
-        tree = ET.parse(path)
+        parser = ET.XMLParser(huge_tree=True)
+        tree = ET.parse(path, parser=parser)
         root = tree.getroot()
 
         return cls.from_xml_element(root)
diff --git a/openmc/model/model.py b/openmc/model/model.py
index a60960b2bad..5194fec1daa 100644
--- a/openmc/model/model.py
+++ b/openmc/model/model.py
@@ -253,7 +253,8 @@ def from_model_xml(cls, path='model.xml'):
         path : str or PathLike
             Path to model.xml file
         """
-        tree = ET.parse(path)
+        parser = ET.XMLParser(huge_tree=True)
+        tree = ET.parse(path, parser=parser)
         root = tree.getroot()
 
         model = cls()
diff --git a/openmc/plots.py b/openmc/plots.py
index b38b51a59c6..c73e3cdf73e 100644
--- a/openmc/plots.py
+++ b/openmc/plots.py
@@ -1508,6 +1508,7 @@ def from_xml(cls, path='plots.xml'):
             Plots collection
 
         """
-        tree = ET.parse(path)
+        parser = ET.XMLParser(huge_tree=True)
+        tree = ET.parse(path, parser=parser)
         root = tree.getroot()
         return cls.from_xml_element(root)
diff --git a/openmc/settings.py b/openmc/settings.py
index 6486d1f2a8e..a6d273901e0 100644
--- a/openmc/settings.py
+++ b/openmc/settings.py
@@ -1952,7 +1952,8 @@ def from_xml(cls, path: PathLike = 'settings.xml'):
             Settings object
 
         """
-        tree = ET.parse(path)
+        parser = ET.XMLParser(huge_tree=True)
+        tree = ET.parse(path, parser=parser)
         root = tree.getroot()
         meshes = _read_meshes(root)
         return cls.from_xml_element(root, meshes)
diff --git a/openmc/tallies.py b/openmc/tallies.py
index b6cd4d13939..ddc5d68ee6c 100644
--- a/openmc/tallies.py
+++ b/openmc/tallies.py
@@ -3304,6 +3304,7 @@ def from_xml(cls, path='tallies.xml'):
             Tallies object
 
         """
-        tree = ET.parse(path)
+        parser = ET.XMLParser(huge_tree=True)
+        tree = ET.parse(path, parser=parser)
         root = tree.getroot()
         return cls.from_xml_element(root)