diff --git a/py/picca/delta_extraction/expected_fluxes/dr16_fixed_eta_expected_flux.py b/py/picca/delta_extraction/expected_fluxes/dr16_fixed_eta_expected_flux.py
index 002fe3ca7..090e5fc54 100644
--- a/py/picca/delta_extraction/expected_fluxes/dr16_fixed_eta_expected_flux.py
+++ b/py/picca/delta_extraction/expected_fluxes/dr16_fixed_eta_expected_flux.py
@@ -62,9 +62,9 @@ def _initialize_get_eta(self):
         # initialize eta factor
         if self.eta_value.endswith(".fits") or self.eta_value.endswith(
                 ".fits.gz"):
-            hdu = fitsio.read(self.eta_value, ext="VAR_FUNC")
-            self.get_eta = interp1d(hdu["loglam"],
-                                    hdu["eta"],
+            hdu = fitsio.FITS(self.eta_value)["VAR_FUNC"]
+            self.get_eta = interp1d(hdu["LOGLAM"].read(),
+                                    hdu["ETA"].read(),
                                     fill_value='extrapolate',
                                     kind='nearest')
         else:
diff --git a/py/picca/delta_extraction/expected_fluxes/dr16_fixed_fudge_expected_flux.py b/py/picca/delta_extraction/expected_fluxes/dr16_fixed_fudge_expected_flux.py
index f19c5217a..7f1c8bfc4 100644
--- a/py/picca/delta_extraction/expected_fluxes/dr16_fixed_fudge_expected_flux.py
+++ b/py/picca/delta_extraction/expected_fluxes/dr16_fixed_fudge_expected_flux.py
@@ -62,9 +62,9 @@ def _initialize_get_fudge(self):
         # initialize fudge factor
         if self.fudge_value.endswith(".fits") or self.fudge_value.endswith(
                 ".fits.gz"):
-            hdu = fitsio.read(self.fudge_value, ext="VAR_FUNC")
-            self.get_fudge = interp1d(hdu["loglam"],
-                                      hdu["fudge"],
+            hdu = fitsio.FITS(self.fudge_value)["VAR_FUNC"]
+            self.get_fudge = interp1d(hdu["LOGLAM"].read(),
+                                      hdu["FUDGE"].read(),
                                       fill_value='extrapolate',
                                       kind='nearest')
         else:
diff --git a/py/picca/delta_extraction/expected_fluxes/dr16_fixed_varlss_expected_flux.py b/py/picca/delta_extraction/expected_fluxes/dr16_fixed_varlss_expected_flux.py
index 8e5b07bd6..1909d4f84 100644
--- a/py/picca/delta_extraction/expected_fluxes/dr16_fixed_varlss_expected_flux.py
+++ b/py/picca/delta_extraction/expected_fluxes/dr16_fixed_varlss_expected_flux.py
@@ -62,9 +62,9 @@ def _initialize_get_var_lss(self):
         # initialize fudge factor
         if self.var_lss_value.endswith(".fits") or self.var_lss_value.endswith(
                 ".fits.gz"):
-            hdu = fitsio.read(self.var_lss_value, ext="VAR_FUNC")
-            self.get_var_lss = interp1d(hdu["loglam"],
-                                        hdu["var_lss"],
+            hdu = fitsio.FITS(self.var_lss_value)["VAR_FUNC"]
+            self.get_var_lss = interp1d(hdu["LOGLAM"].read(),
+                                        hdu["VAR_LSS"].read(),
                                         fill_value='extrapolate',
                                         kind='nearest')
         else: