diff --git a/KaitaiStream.cs b/KaitaiStream.cs
index 5a1bf06..936dd81 100644
--- a/KaitaiStream.cs
+++ b/KaitaiStream.cs
@@ -307,11 +307,9 @@ namespace Kaitai
 
             // raw mask with required number of 1s, starting from lowest bit
             ulong mask = GetMaskOnes(n);
-            // shift mask to align with highest bits available in "bits"
+            // shift "bits" to align the highest bits with the mask & derive reading result
             int shiftBits = BitsLeft - n;
-            mask = mask << shiftBits;
-            // derive reading result
-            ulong res = (Bits & mask) >> shiftBits;
+            ulong res = (Bits >> shiftBits) & mask;
             // clear top bits that we've just read => AND with 1s
             BitsLeft -= n;
             mask = GetMaskOnes(BitsLeft);