diff --git a/src/pineko/check.py b/src/pineko/check.py
index 68365ae1..aad141d3 100644
--- a/src/pineko/check.py
+++ b/src/pineko/check.py
@@ -67,6 +67,31 @@ def check_grid_and_eko_compatible(pineappl_grid, operators, xif):
         raise ValueError("x grid in pineappl grid and eko operator are NOT compatible!")
 
 
+def is_fonll_b(fns, lumi):
+    """Check if the fktable we are computing is a DIS FONLL-B fktable.
+
+    Parameters
+    ----------
+        fns : str
+            flavor number scheme (from the theory card)
+        lumi : list(list(tuple))
+            luminosity info
+
+    Returns
+    -------
+            : bool
+            true if the fktable is a FONLL-B DIS fktable
+    """
+    for lists in lumi:
+        for el in lists:
+            if not (10 < abs(el[1]) < 17):
+                # in this case we are sure it is not DIS so for sure it is not FONLL-B
+                return False
+    if fns == "FONLL-B":
+        return True
+    return False
+
+
 def contains_fact(grid):
     """Check whether factorization scale-variations are available in the pineappl grid.
 
diff --git a/src/pineko/theory.py b/src/pineko/theory.py
index e27b4e8c..69091257 100644
--- a/src/pineko/theory.py
+++ b/src/pineko/theory.py
@@ -351,11 +351,11 @@ def fk(self, name, grid_path, tcard, pdf):
         xir = tcard["XIR"]
         xif = tcard["XIF"]
         ftr = tcard["fact_to_ren_scale_ratio"]
-        pineappl_grid = pineappl.grid.Grid.read(grid_path)
+        grid = pineappl.grid.Grid.read(grid_path)
         if not np.isclose(xir, 1.0):
-            check.contains_ren(pineappl_grid)
+            check.contains_ren(grid)
         if not (np.isclose(xif, 1.0) and np.isclose(ftr, 1.0)):
-            check.contains_fact(pineappl_grid)
+            check.contains_fact(grid)
         # setup data
         eko_filename = self.ekos_path() / f"{name}.tar"
         fk_filename = self.fks_path / f"{name}.{parser.EXT}"
@@ -364,6 +364,12 @@ def fk(self, name, grid_path, tcard, pdf):
                 rich.print(f"Skipping existing FK Table {fk_filename}")
                 return
         max_as = 1 + int(tcard["PTO"])
+        # Check if we are computing FONLL-B fktable and eventually change max_as
+        if check.is_fonll_b(
+            tcard["FNS"],
+            grid.lumi(),
+        ):
+            max_as += 1
         max_al = 0
         # collect alpha_s
         # TODO: move this down to evolve.evolve_grid when output contains cards
@@ -391,7 +397,7 @@ def fk(self, name, grid_path, tcard, pdf):
             f"with max_as={max_as}, max_al={max_al}, xir={xir}, xif={xif}",
         )
         _grid, _fk, comparison = evolve.evolve_grid(
-            pineappl_grid,
+            grid,
             eko_filename,
             fk_filename,
             max_as,
diff --git a/tests/test_check.py b/tests/test_check.py
index e7374fa7..4798eae1 100644
--- a/tests/test_check.py
+++ b/tests/test_check.py
@@ -8,7 +8,6 @@
 
 import pineko.check
 
-
 class Fake_grid:
     def __init__(self, order_list):
         self.orderlist = order_list
@@ -49,3 +48,14 @@ def test_contains_ren():
     mygrid_nofact = Fake_grid(order_list)
     with pytest.raises(ValueError):
         pineko.check.contains_ren(mygrid_nofact)
+
+
+def test_is_fonll_b():
+    fns = "FONLL-B"
+    lumi = [[(1, 11, 3, 4), (3, 11, 5, 6)], [(9, 11, 0, 3), (8, 11, -2, -1)]]
+    assert pineko.check.is_fonll_b(fns, lumi) is True
+    lumi.append([(1, 11, 2, 3), (2, 4, 5, 6)])
+    assert pineko.check.is_fonll_b(fns, lumi) is False
+    lumi.pop(-1)
+    fns = "FONLL-C"
+    assert pineko.check.is_fonll_b(fns, lumi) is False