diff --git a/utils/opatio/src/opatio/opat/opat.py b/utils/opatio/src/opatio/opat/opat.py
index 278b62a..8e3cc83 100644
--- a/utils/opatio/src/opatio/opat/opat.py
+++ b/utils/opatio/src/opatio/opat/opat.py
@@ -48,18 +48,23 @@ class OPATTable:
     logT: Iterable[float]        #< Logarithm of T values
     logKappa: Iterable[Iterable[float]] #< Logarithm of Kappa values
 
-defaultHeader = Header(
-    magic="OPAT",
-    version=1,
-    numTables=0,
-    headerSize=256,
-    indexOffset=0,
-    creationDate=datetime.now().strftime("%b %d, %Y"),
-    sourceInfo="no source provided by user",
-    comment="default header",
-    numIndex=2,
-    reserved=b"\x00" * 24
-)
+def make_default_header() -> Header:
+    """
+    @brief Create a default header for an OPAT file.
+    @return The default header.
+    """
+    return Header(
+        magic="OPAT",
+        version=1,
+        numTables=0,
+        headerSize=256,
+        indexOffset=0,
+        creationDate=datetime.now().strftime("%b %d, %Y"),
+        sourceInfo="no source provided by user",
+        comment="default header",
+        numIndex=2,
+        reserved=b"\x00" * 24
+    )
 
 class OpatIO:
     """
@@ -103,7 +108,7 @@ class OpatIO:
             Save the OPAT file as a binary file.
     """
     def __init__(self):
-        self.header: Header = defaultHeader
+        self.header: Header = make_default_header()
         self.tables: List[Tuple[Tuple[float, float], OPATTable]] = []
 
     @staticmethod