diff --git a/src/qibo/models/qgan.py b/src/qibo/models/qgan.py
index b209e0f584..c14b5caf19 100644
--- a/src/qibo/models/qgan.py
+++ b/src/qibo/models/qgan.py
@@ -259,11 +259,11 @@ def generate_real_samples(samples, distribution, real_samples):
         # determine half the size of one batch, for updating the discriminator
         half_samples = int(self.batch_samples / 2)
         if self.initial_params is not None:
-            initial_params = tf.Variable(self.initial_params, dtype=tf.complex64)
+            initial_params = tf.Variable(self.initial_params, dtype=tf.complex128)
         else:
             n = 10 * self.layers * self.nqubits + 2 * self.nqubits
             initial_params = tf.Variable(
-                np.random.uniform(-0.15, 0.15, n), dtype=tf.complex64
+                np.random.uniform(-0.15, 0.15, n), dtype=tf.complex128
             )
 
         optimizer = tf.optimizers.Adadelta(  # pylint: disable=no-member