diff --git a/pysollib/hint.py b/pysollib/hint.py
index a01b37af..b1f48173 100644
--- a/pysollib/hint.py
+++ b/pysollib/hint.py
@@ -947,13 +947,17 @@ class FreeCellSolver_Hint(Base_Solver_Hint):
                         put_str(game.reserves[i], str_)
                 continue
             m = re.match(r'^:?\s*(.*)', line)
-            assert m
             for str_ in my_find_re(r'(' + CARD_RE + r')', m,
                                    "Invalid column text"):
                 put_str(game.rows[stack_idx], str_)
 
             stack_idx += 1
-        assert len(cards()) == 0
+        if len(cards()) > 0:
+            raise PySolHintLayoutImportError(
+                "Missing cards in input",
+                [solver.card2str1(c) for c in cards()],
+                -1
+            )
 
     def calcBoardString(self):
         game = self.game
diff --git a/tests/lib/pysol_tests/import_file1.py b/tests/lib/pysol_tests/import_file1.py
index 654df7de..7d1d350e 100644
--- a/tests/lib/pysol_tests/import_file1.py
+++ b/tests/lib/pysol_tests/import_file1.py
@@ -158,6 +158,15 @@ KD QC 5C QH 6S 3D
             return
         self.fail("No exception thrown.")
 
+    def test_throw_error_on_missing_cards(self):
+        try:
+            self._calc_hint('tests/unit/data/624-missing-cards.board')
+        except PySolHintLayoutImportError as err:
+            self.assertEqual(err.msg, "Missing cards in input")
+            self.assertEqual(err.cards, ["5H"])
+            return
+        self.fail("No exception thrown.")
+
 
 def mymain():
     from pycotap import TAPTestRunner
diff --git a/tests/unit/data/624-missing-cards.board b/tests/unit/data/624-missing-cards.board
new file mode 100644
index 00000000..08f9df31
--- /dev/null
+++ b/tests/unit/data/624-missing-cards.board
@@ -0,0 +1,8 @@
+: KC 6H 4C QS 2D 4S AS
+: 4H TH 2S JH 2H 9S AH
+: 3S 6C 9H AD KH QD 7C
+: 3C JS KS TC 9C 8C
+: 4D 9D 7S JC 5D TS
+: KD QC 5C QH 6S 3D
+: 5S JD 8D 6D TD 8H
+: 8S 7H 3H 2C AC 7D