diff --git a/big-integer/big-integer-tests.ts b/big-integer/big-integer-tests.ts
index 92633d2871..fd08f89a14 100644
--- a/big-integer/big-integer-tests.ts
+++ b/big-integer/big-integer-tests.ts
@@ -6,7 +6,7 @@ var noArgument = bigInt(),
     stringArgument = bigInt( "75643564363473453456342378564387956906736546456235345" ),
     baseArgumentInt = bigInt( "101010", 2 ),
     baseArgumentStr = bigInt( "101010", "2" ),
-    baseArgumentBi  = bigInt( "101010", bigInt( 2 ) ), 
+    baseArgumentBi  = bigInt( "101010", bigInt( 2 ) ),
     bigIntArgument = bigInt( noArgument );
 
 // method tests
@@ -26,13 +26,13 @@ isBigInteger = x.add( 0 );
 isBigInteger = x.add( x );
 isBigInteger = x.add( "100" );
 
-isBigInteger = x.compare( 0 );
-isBigInteger = x.compare( x );
-isBigInteger = x.compare( "100" );
+isNumber = x.compare( 0 );
+isNumber = x.compare( x );
+isNumber = x.compare( "100" );
 
-isBigInteger = x.compareAbs( 0 );
-isBigInteger = x.compareAbs( x );
-isBigInteger = x.compareAbs( "100" );
+isNumber = x.compareAbs( 0 );
+isNumber = x.compareAbs( x );
+isNumber = x.compareAbs( "100" );
 
 isBigInteger = x.divide( 0 );
 isBigInteger = x.divide( x );
diff --git a/big-integer/big-integer.d.ts b/big-integer/big-integer.d.ts
index 9e9127e830..05b1e10a7b 100644
--- a/big-integer/big-integer.d.ts
+++ b/big-integer/big-integer.d.ts
@@ -134,24 +134,24 @@ interface BigInteger {
      * Performs a comparison between two numbers. If the numbers are equal, it returns 0.
      * If the first number is greater, it returns 1. If the first number is lesser, it returns -1.
      */
-    compare( number: number ): BigInteger;
+    compare( number: number ): number;
     /**
      * Performs a comparison between two numbers. If the numbers are equal, it returns 0.
      * If the first number is greater, it returns 1. If the first number is lesser, it returns -1.
      */
-    compare( number: BigInteger ): BigInteger;
+    compare( number: BigInteger ): number;
     /**
      * Performs a comparison between two numbers. If the numbers are equal, it returns 0.
      * If the first number is greater, it returns 1. If the first number is lesser, it returns -1.
      */
-    compare( number: string ): BigInteger;
+    compare( number: string ): number;
 
     /** Performs a comparison between the absolute value of two numbers. */
-    compareAbs( number: number ): BigInteger;
+    compareAbs( number: number ): number;
     /** Performs a comparison between the absolute value of two numbers. */
-    compareAbs( number: BigInteger ): BigInteger;
+    compareAbs( number: BigInteger ): number;
     /** Performs a comparison between the absolute value of two numbers. */
-    compareAbs( number: string ): BigInteger;
+    compareAbs( number: string ): number;
 
     /** Checks if two numbers are equal. */
     equals( number: number ): boolean;