diff --git a/einx/expr/solver.py b/einx/expr/solver.py
index 3811415..fd95715 100644
--- a/einx/expr/solver.py
+++ b/einx/expr/solver.py
@@ -20,10 +20,11 @@ def __rmul__(self, other):
 
 
 class Variable(Expression):
-    def __init__(self, id, name):
+    def __init__(self, id, name, integer=True):
         Expression.__init__(self)
         self.id = id
         self.name = name
+        self.integer = integer
 
     def __iter__(self):
         yield self
@@ -38,7 +39,7 @@ def __str__(self):
         return f"{self.name}"
 
     def sympy(self):
-        return sympy.Symbol(self.id)
+        return sympy.Symbol(self.id, integer=self.integer)
 
 
 class Constant(Expression):
diff --git a/test/test_shapes.py b/test/test_shapes.py
index 4cb9052..eea9142 100644
--- a/test/test_shapes.py
+++ b/test/test_shapes.py
@@ -233,6 +233,11 @@ def w(shape):
     assert einx.dot("... b, ... -> b", x, y).shape == (10,)
     assert einx.dot("[...] b -> b", x, y).shape == (10,)
 
+    k = setup.full((2, 4, 100))
+    v = setup.full((2, 4, 100))
+    with pytest.raises(Exception):
+        einx.dot("b t (h ck), b t (h cv) -> b h ck cv", k, v, h=32, graph=True)
+
 
 @pytest.mark.parametrize("test", conftest.tests)
 def test_shape_reduce(test):