diff --git a/cpmpy/solvers/exact.py b/cpmpy/solvers/exact.py
index 5a290a6de..01c54287b 100644
--- a/cpmpy/solvers/exact.py
+++ b/cpmpy/solvers/exact.py
@@ -37,6 +37,8 @@
 from ..transformations.normalize import toplevel_list
 from ..expressions.globalconstraints import DirectConstraint
 from ..exceptions import NotSupportedError
+from ..expressions.utils import flatlist
+
 import numpy as np
 import numbers
 
@@ -589,6 +591,10 @@ def solution_hint(self, cpm_vars, vals):
         :param cpm_vars: list of CPMpy variables
         :param vals: list of (corresponding) values for the variables
         """
+
+        cpm_vars = flatlist(cpm_vars)
+        vals = flatlist(vals)
+        assert (len(cpm_vars) == len(vals)), "Variables and values must have the same size for hinting"
         try:
             pkg_resources.require("exact>=1.1.5")
             self.xct_solver.setSolutionHints(self.solver_vars(cpm_vars), vals)
diff --git a/cpmpy/solvers/ortools.py b/cpmpy/solvers/ortools.py
index 8878d9d30..d4879761e 100644
--- a/cpmpy/solvers/ortools.py
+++ b/cpmpy/solvers/ortools.py
@@ -32,7 +32,7 @@
 from ..expressions.globalconstraints import DirectConstraint
 from ..expressions.variables import _NumVarImpl, _IntVarImpl, _BoolVarImpl, NegBoolView, boolvar
 from ..expressions.globalconstraints import GlobalConstraint
-from ..expressions.utils import is_num, is_any_list, eval_comparison
+from ..expressions.utils import is_num, is_any_list, eval_comparison, flatlist
 from ..transformations.decompose_global import decompose_in_tree
 from ..transformations.get_variables import get_variables
 from ..transformations.flatten_model import flatten_constraint, flatten_objective
@@ -521,6 +521,10 @@ def solution_hint(self, cpm_vars, vals):
         :param vals: list of (corresponding) values for the variables
         """
         self.ort_model.ClearHints() # because add just appends
+
+        cpm_vars = flatlist(cpm_vars)
+        vals = flatlist(vals)
+        assert (len(cpm_vars) == len(vals)), "Variables and values must have the same size for hinting"
         for (cpm_var, val) in zip(cpm_vars, vals):
             self.ort_model.AddHint(self.solver_var(cpm_var), val)
 
diff --git a/cpmpy/solvers/pysat.py b/cpmpy/solvers/pysat.py
index 022c6056d..66003b7e1 100644
--- a/cpmpy/solvers/pysat.py
+++ b/cpmpy/solvers/pysat.py
@@ -34,7 +34,7 @@
 from ..expressions.core import Expression, Comparison, Operator, BoolVal
 from ..expressions.variables import _BoolVarImpl, NegBoolView, boolvar
 from ..expressions.globalconstraints import DirectConstraint
-from ..expressions.utils import is_any_list, is_int
+from ..expressions.utils import is_int, flatlist
 from ..transformations.decompose_global import decompose_in_tree
 from ..transformations.get_variables import get_variables
 from ..transformations.flatten_model import flatten_constraint
@@ -316,6 +316,11 @@ def solution_hint(self, cpm_vars, vals):
         :param cpm_vars: list of CPMpy variables
         :param vals: list of (corresponding) values for the variables
         """
+
+        cpm_vars = flatlist(cpm_vars)
+        vals = flatlist(vals)
+        assert (len(cpm_vars) == len(vals)), "Variables and values must have the same size for hinting"
+
         literals = []
         for (cpm_var, val) in zip(cpm_vars, vals):
             lit = self.solver_var(cpm_var)
diff --git a/tests/test_solvers_solhint.py b/tests/test_solvers_solhint.py
index 9d7c24324..00dbeac61 100644
--- a/tests/test_solvers_solhint.py
+++ b/tests/test_solvers_solhint.py
@@ -32,6 +32,9 @@ def test_hints(self):
                 slv.solution_hint([a,b], [True,True])
                 self.assertTrue(slv.solve(**args)) # should also work with an UNSAT hint
 
+                slv.solution_hint([a,[b]], [[[False]], True]) # check nested lists
+                self.assertTrue(slv.solve(**args))
+
             except NotSupportedError:
                 continue