diff --git a/graxpert/astroimage.py b/graxpert/astroimage.py
index 3d3ba60..86cb685 100644
--- a/graxpert/astroimage.py
+++ b/graxpert/astroimage.py
@@ -317,6 +317,11 @@ def xisf_imagedata_2_fitsheader(self):
                 if key in commentary_keys:
                     if value == "":
                         value = comment
+                
+                if value.isdigit():
+                    value = int(value)
+                elif value.isdecimal():
+                    value = float(value)
                         
                 self.fits_header[key] = (value, comment)