diff --git a/types/mathjs/index.d.ts b/types/mathjs/index.d.ts
index cdecc3e1b4..92015f72ff 100644
--- a/types/mathjs/index.d.ts
+++ b/types/mathjs/index.d.ts
@@ -543,7 +543,7 @@ declare namespace math { // tslint:disable-line strict-export-declare-modifiers
 		/**
 		 * Create a number or convert a string, boolean, or unit to a number. When value is a matrix, all elements will be converted to number.
 		 */
-		number(value?: string|number|boolean|MathArray|Matrix|Unit|BigNumber): number|MathArray|Matrix;
+		number(value?: string|number|boolean|MathArray|Matrix|Unit|BigNumber|Fraction): number|MathArray|Matrix;
 		number(unit: Unit, valuelessUnit: Unit|string): number|MathArray|Matrix;
 
 		/**