diff --git a/big-integer/big-integer.d.ts b/big-integer/big-integer.d.ts
index dfadc4962..8b688d47c 100644
--- a/big-integer/big-integer.d.ts
+++ b/big-integer/big-integer.d.ts
@@ -1,6 +1,6 @@
 // Type definitions for BigInteger.js
 // Project: https://github.com/peterolson/BigInteger.js
-// Definitions by: Ingo Bürk <https://github.com/Airblader>
+// Definitions by: Ingo Bürk <https://github.com/Airblader>, Roel van Uden <https://github.com/Deathspike>
 // Definitions: https://github.com/borisyankov/DefinitelyTyped
 
 interface BigInteger {
@@ -167,6 +167,34 @@ interface BigInteger {
     /** Checks if two numbers are not equal. */
     notEquals( number: string ): boolean;
 
+    /** Performs the bitwise AND operation. */
+    and( number: number ): BigInteger;
+    /** Performs the bitwise AND operation. */
+    and( number: BigInteger ): BigInteger;
+    /** Performs the bitwise AND operation. */
+    and( number: string ): BigInteger;
+
+    /** Performs the bitwise NOT operation. */
+    not( number: number ): BigInteger;
+    /** Performs the bitwise NOT operation. */
+    not( number: BigInteger ): BigInteger;
+    /** Performs the bitwise NOT operation. */
+    not( number: string ): BigInteger;
+
+    /** Performs the bitwise OR operation. */
+    or( number: number ): BigInteger;
+    /** Performs the bitwise OR operation. */
+    or( number: BigInteger ): BigInteger;
+    /** Performs the bitwise OR operation. */
+    or( number: string ): BigInteger;
+
+    /** Performs the bitwise XOR operation. */
+    xor( number: number ): BigInteger;
+    /** Performs the bitwise XOR operation. */
+    xor( number: BigInteger ): BigInteger;
+    /** Performs the bitwise XOR operation. */
+    xor( number: string ): BigInteger;
+
     /** Converts a bigInt into a native Javascript number. Loses precision for numbers outside the range. */
     toJSNumber(): number;