diff --git a/validphys2/src/validphys/config.py b/validphys2/src/validphys/config.py
index 099e3e105f..95d285160f 100644
--- a/validphys2/src/validphys/config.py
+++ b/validphys2/src/validphys/config.py
@@ -1051,14 +1051,22 @@ def parse_use_t0(self, do_use_t0: bool):
 
     # TODO: Find a good name for this
     def produce_t0set(
-        self, t0pdfset=None, use_t0_sampling=False, use_t0_fitting=True,
+        self, t0pdfset=None, use_t0_sampling=False, use_t0_fitting=False, use_t0=False
     ):
         """Return the t0set if use_t0 is True and None otherwise. Raises an
-        error if t0 is requested but no t0set is given.
+        error if t0 is requested but no t0set is given or if an ambiguous combination is requested
+        Note that ``n3fit`` will set ``use_t0_fitting`` to `True` by default.
         """
-        if use_t0_sampling or use_t0_fitting:
+        if not use_t0:
+            # Check that sampling and fitting t0 are also set to False
+            if use_t0_sampling:
+                raise ConfigError("Incompatible: sampling::use_t0 is True, but use_t0 is False")
+            if use_t0_fitting:
+                raise ConfigError("Incompatible: fitting::use_t0 is True, but use_t0 is False")
+        if use_t0:
             if not t0pdfset:
-                raise ConfigError("Setting use_t0 requires specifying a valid t0pdfset")
+                raise ConfigError("""Setting use_t0, use_t0_sampling or use_t0_fitting
+                                  requires specifying a valid t0pdfset""")
             return t0pdfset
         return None