diff --git a/ChocolArm64/Decoder/AOpCodeSimdShImm.cs b/ChocolArm64/Decoder/AOpCodeSimdShImm.cs
index 6c8398817c..e6d5210f2f 100644
--- a/ChocolArm64/Decoder/AOpCodeSimdShImm.cs
+++ b/ChocolArm64/Decoder/AOpCodeSimdShImm.cs
@@ -10,7 +10,7 @@ namespace ChocolArm64.Decoder
         {
             Imm = (OpCode >> 16) & 0x7f;
 
-            Size = ABitUtils.HighestBitSet32(Imm >> 3);
+            Size = ABitUtils.HighestBitSetNibble(Imm >> 3);
         }
     }
-}
\ No newline at end of file
+}