diff --git a/riptable/rt_categorical.py b/riptable/rt_categorical.py
index 31b98073..99b6cf5b 100644
--- a/riptable/rt_categorical.py
+++ b/riptable/rt_categorical.py
@@ -3105,8 +3105,8 @@ def isin(self, values) -> FastArray:
         if isinstance(x, (list, np.ndarray)):
             if len(x) > 1:
                 return ismember(self, x)[0]
-            elif np.isscalar(x[0]):
-                return self == x[0]
+            elif np.isscalar(x):
+                return self == x
         return self == x
 
     # -------------------------------------------------------