diff --git a/catterplot/core.py b/catterplot/core.py
index 498ed41..ca3ba87 100644
--- a/catterplot/core.py
+++ b/catterplot/core.py
@@ -80,7 +80,7 @@ def catter(x, y, s=40, c=None, cat='random', alpha=1, ax=None, cmap=None,
         cats = np.random.randint(n_cats(), size=len(x))
     else:
         try:
-            cats = np.ones(len(x)) * cat
+            cats = [cat] * len(x)
         except TypeError as e:
             raise TypeError('`cat` argument needs to be "random", a scalar, or match the input.', e)