diff --git a/src/endf/material.py b/src/endf/material.py
index 3965603..fae102f 100644
--- a/src/endf/material.py
+++ b/src/endf/material.py
@@ -153,14 +153,14 @@ def __init__(self, filename_or_obj: Union[PathLike, TextIO], encoding: Optional[
                 fh.readline()
                 break
 
-            section_text = ''
+            section_lines = []
             while True:
                 line = fh.readline()
                 if line[72:75] == '  0':
                     break
                 else:
-                    section_text += line
-            self.section_text[MF, MT] = section_text
+                    section_lines.append(line)
+            self.section_text[MF, MT] = "".join(section_lines)
 
         if need_to_close:
             fh.close()