1diff --git a/src/Formulas/Statistical.ts b/src/Formulas/Statistical.ts
 2index 32e4baa..504f341 100644
 3--- a/src/Formulas/Statistical.ts
 4+++ b/src/Formulas/Statistical.ts
 5@@ -532,7 +532,6 @@ var FDIST$LEFTTAILED = function (...values) : number|undefined|boolean {
 6  * @param values[2] deg_freedom2 - Required. The denominator degrees of freedom.
 7  * @returns {number} inverse of the (right-tailed) F probability distribution
 8  * @constructor
 9- * TODO: This function needs to be tested more thoroughly.
10  */
11 var FINV = function (...values) : number {
12   /**
13diff --git a/tests/Formulas/StatisticalTest.ts b/tests/Formulas/StatisticalTest.ts
14index e16c8de..3b000fb 100644
15--- a/tests/Formulas/StatisticalTest.ts
16+++ b/tests/Formulas/StatisticalTest.ts
17@@ -241,7 +241,19 @@ test("EXPONDIST", function(){
18 
19 test("FINV", function(){
20   assertEquals(FINV(0.42, 2, 3), 1.174597274485816);
21+  assertEquals(FINV(0.42, 2, 5), 1.0370426242728021);
22+  assertEquals(FINV(0.42, 33, 5), 1.303222112500911);
23+  assertEquals(FINV(["0.42"], [33, []], [5]), 1.303222112500911);
24   assertEquals(FINV("0.42", 2, 3), 1.174597274485816);
25+  catchAndAssertEquals(function() {
26+    FINV();
27+  }, ERRORS.NA_ERROR);
28+  catchAndAssertEquals(function() {
29+    FINV(0.42, 2, 4, 4);
30+  }, ERRORS.NA_ERROR);
31+  catchAndAssertEquals(function() {
32+    FINV(0.42, 2, []);
33+  }, ERRORS.REF_ERROR);
34   catchAndAssertEquals(function() {
35     FINV(-10, 2, 3);
36   }, ERRORS.NUM_ERROR);