diff --git a/src/runtime/lpython/lpython.py b/src/runtime/lpython/lpython.py
index cf5c7d4de9..b511b5cfac 100644
--- a/src/runtime/lpython/lpython.py
+++ b/src/runtime/lpython/lpython.py
@@ -708,5 +708,10 @@ def __call__(self, *args, **kwargs):
             self.fn_name)
         return function(*args, **kwargs)
 
-def bitnot(x):
-    return ~x
+def bitnot(x, bitsize):
+    return (~x) % (2 ** bitsize)
+
+bitnot_u8 = lambda x: bitnot(x, 8)
+bitnot_u16 = lambda x: bitnot(x, 16)
+bitnot_u32 = lambda x: bitnot(x, 32)
+bitnot_u64 = lambda x: bitnot(x, 64)