diff --git a/interfere/interventions.py b/interfere/interventions.py
index 6346a05..7f1a82b 100644
--- a/interfere/interventions.py
+++ b/interfere/interventions.py
@@ -150,11 +150,11 @@ def __init__(
             intervention([10.0, 4.0, 4.0], 0) == [1.6, 4.0, 0.7] # (True.)
         """
         # The case where indexs and constants are floats or ints
-        if isinstance(intervened_idxs, int) and isinstance(constants, (int, float)):
-            i = intervened_idxs
-            c = float(constants)
-            intervened_idxs = [intervened_idxs]
-            constants = [c]
+        if isinstance(intervened_idxs, (int, float)):
+            intervened_idxs = [int(intervened_idxs)]
+            
+        if isinstance(constants, (int, float)):
+            constants = [float(constants)]
 
         if len(constants) != len(intervened_idxs):
             raise ValueError(