diff --git a/specs/core/0_beacon-chain.md b/specs/core/0_beacon-chain.md
index 0556f3178a..5c67181376 100644
--- a/specs/core/0_beacon-chain.md
+++ b/specs/core/0_beacon-chain.md
@@ -1028,10 +1028,7 @@ def is_power_of_two(value: int) -> bool:
     """
     Check if ``value`` is a power of two integer.
     """
-    if value == 0:
-        return False
-    else:
-        return 2**int(math.log2(value)) == value
+    return (value > 0) and (value & (value - 1) == 0)
 ```
 
 ### `int_to_bytes1`, `int_to_bytes2`, ...