diff --git a/tupak/core/likelihood.py b/tupak/core/likelihood.py
index 3470c635b26a8cfdecee1bdf46a327901f6899c7..562b79898184d10a72a1394550cf49c3c1fcaa9b 100644
--- a/tupak/core/likelihood.py
+++ b/tupak/core/likelihood.py
@@ -204,7 +204,7 @@ class PoissonLikelihood(Analytical1DLikelihood):
 
     @y.setter
     def y(self, y):
-        if isinstance(y, int):
+        if not isinstance(y, np.ndarray):
             y = np.array([y])
         # check array is a non-negative integer array
         if y.dtype.kind not in 'ui' or np.any(y < 0):