diff --git a/grove/deutsch_jozsa/deutsch_jozsa.py b/grove/deutsch_jozsa/deutsch_jozsa.py
index 51c962c..1b21910 100644
--- a/grove/deutsch_jozsa/deutsch_jozsa.py
+++ b/grove/deutsch_jozsa/deutsch_jozsa.py
@@ -56,8 +56,8 @@ def is_constant(self, cxn, bitstring_map):
         returned_bitstring = cxn.run_and_measure(self.deutsch_jozsa_circuit, self.computational_qubits)
         # We are only running a single shot, so we are only interested in the first element.
         bitstring = np.array(returned_bitstring, dtype=int)
-        constant = all([bit == 0 for bit in bitstring])
-        return constant
+        constant = np.array([bit == 0 for bit in bitstring])
+        return constant.all()
 
     def _init_attr(self, bitstring_map):
         """