diff --git a/src/pineko/check.py b/src/pineko/check.py
index 47c85771..a6f6b96a 100644
--- a/src/pineko/check.py
+++ b/src/pineko/check.py
@@ -76,15 +76,19 @@ def in1d(a, b, rtol=1e-05, atol=1e-08):
     )
 
 
-def check_grid_and_eko_compatible(pineappl_grid, operators, xif, max_as, max_al):
-    """Check whether the EKO operators and the PineAPPL grid are compatible.
+def check_grid_and_eko_compatible(
+    pineappl_grid, eko_xgrid, eko_mu2, xif, max_as, max_al
+):
+    """Check whether the EKO operator and the PineAPPL grid are compatible.
 
     Parameters
     ----------
     pineappl_grid : pineappl.grid.Grid
         grid
-    operators : eko.EKO
-        operators
+    eko_xgrid : list
+        eko interpolation xgrid
+    eko_mu2: float
+        eko mu2 scale
     xif : float
         factorization scale variation
     max_as: int
@@ -95,7 +99,7 @@ def check_grid_and_eko_compatible(pineappl_grid, operators, xif, max_as, max_al)
     Raises
     ------
     ValueError
-        If the operators and the grid are not compatible.
+        If the operator and the grid are not compatible.
     """
     order_mask = pineappl.grid.Order.create_mask(
         pineappl_grid.orders(), max_as, max_al, True
@@ -104,14 +108,12 @@ def check_grid_and_eko_compatible(pineappl_grid, operators, xif, max_as, max_al)
     x_grid = evol_info.x1
     muf2_grid = evol_info.fac1
     # Q2 grid
-    if not np.all(
-        in1d(np.unique(list(operators.mu2grid)), xif * xif * np.array(muf2_grid))
-    ):
+    if not np.all(in1d(np.array([eko_mu2]), xif * xif * np.array(muf2_grid))):
         raise ValueError(
             "Q2 grid in pineappl grid and eko operator are NOT compatible!"
         )
     # x-grid
-    if not np.all(in1d(np.unique(operators.xgrid.tolist()), np.array(x_grid))):
+    if not np.all(in1d(np.unique(eko_xgrid), np.array(x_grid))):
         raise ValueError("x grid in pineappl grid and eko operator are NOT compatible!")
 
 
diff --git a/src/pineko/cli/check.py b/src/pineko/cli/check.py
index a515c017..19794744 100644
--- a/src/pineko/cli/check.py
+++ b/src/pineko/cli/check.py
@@ -38,13 +38,14 @@ def sub_compatibility(grid_path, operator_path, xif, max_as, max_al):
     """
     pineappl_grid = pineappl.grid.Grid.read(grid_path)
     with eko.EKO.read(operator_path) as operators:
-        try:
-            check.check_grid_and_eko_compatible(
-                pineappl_grid, operators, xif, max_as, max_al
-            )
-            rich.print("[green]Success:[/] grids are compatible")
-        except ValueError as e:
-            rich.print("[red]Error:[/]", e)
+        for (q2, _), _ in operators.items():
+            try:
+                check.check_grid_and_eko_compatible(
+                    pineappl_grid, operators.xgrid.tolist(), q2, xif, max_as, max_al
+                )
+            except ValueError as e:
+                rich.print("[red]Error:[/]", e)
+    rich.print("[green]Success:[/] grids and eko are compatible.")
 
 
 @dataclass
diff --git a/src/pineko/evolve.py b/src/pineko/evolve.py
index 1842af6a..cf327ce7 100644
--- a/src/pineko/evolve.py
+++ b/src/pineko/evolve.py
@@ -365,11 +365,6 @@ def evolve_grid(
     tcard = operators1.theory_card
     opcard = operators1.operator_card
 
-    # TODO: do we still want to check here or only later ?
-    check.check_grid_and_eko_compatible(grid, operators1, xif, max_as, max_al)
-    if operators2 is not None:
-        check.check_grid_and_eko_compatible(grid, operators2, xif, max_as, max_al)
-
     # PineAPPL wants alpha_s = 4*pi*a_s
     # remember that we already accounted for xif in the opcard generation
     evmod = eko.couplings.couplings_mod_ev(opcard.configs.evolution_method)
@@ -404,6 +399,8 @@ def prepare(operator):
         """Match the raw operator with its relevant metadata."""
         for (q2, _), op in operator.items():
             op = xgrid_reshape(op, operator.xgrid)
+            # TODO: this check here could be dropped ?
+            check.check_grid_and_eko_compatible(grid, x_grid, q2, xif, max_as, max_al)
             info = PyOperatorSliceInfo(
                 fac0=operator.mu20,
                 x0=operator.xgrid.tolist(),