diff --git a/S7.Net/Types/Boolean.cs b/S7.Net/Types/Boolean.cs
index cfb52f8..f7bc83e 100644
--- a/S7.Net/Types/Boolean.cs
+++ b/S7.Net/Types/Boolean.cs
@@ -14,20 +14,51 @@
         }
 
         /// <summary>
-        /// Sets the value of a bit to 1 (true), given the address of the bit
+        /// Sets the value of a bit to 1 (true), given the address of the bit. Returns
+        /// a copy of the value with the bit set.
         /// </summary>
+        /// <param name="value">The input value to modify.</param>
+        /// <param name="bit">The index (zero based) of the bit to set.</param>
+        /// <returns>The modified value with the bit at index set.</returns>
         public static byte SetBit(byte value, int bit)
         {
-            return (byte)((value | (1 << bit)) & 0xFF);
+            SetBit(ref value, bit);
+
+            return value;
+        }
+
+        /// <summary>
+        /// Sets the value of a bit to 1 (true), given the address of the bit.
+        /// </summary>
+        /// <param name="value">The value to modify.</param>
+        /// <param name="bit">The index (zero based) of the bit to set.</param>
+        public static void SetBit(ref byte value, int bit)
+        {
+            value = (byte) ((value | (1 << bit)) & 0xFF);
+        }
+
+        /// <summary>
+        /// Resets the value of a bit to 0 (false), given the address of the bit. Returns
+        /// a copy of the value with the bit cleared.
+        /// </summary>
+        /// <param name="value">The input value to modify.</param>
+        /// <param name="bit">The index (zero based) of the bit to clear.</param>
+        /// <returns>The modified value with the bit at index cleared.</returns>
+        public static byte ClearBit(byte value, int bit)
+        {
+            ClearBit(ref value, bit);
+
+            return value;
         }
 
         /// <summary>
         /// Resets the value of a bit to 0 (false), given the address of the bit
         /// </summary>
-        public static byte ClearBit(byte value, int bit)
+        /// <param name="value">The input value to modify.</param>
+        /// <param name="bit">The index (zero based) of the bit to clear.</param>
+        public static void ClearBit(ref byte value, int bit)
         {
-            return (byte)((value & (~(1 << bit))) & 0xFF);
+            value = (byte) (value & ~(1 << bit) & 0xFF);
         }
-
     }
 }