diff --git a/tests/planets/mars.test.js b/tests/planets/mars.test.js
index 60437db..ceefab9 100644
--- a/tests/planets/mars.test.js
+++ b/tests/planets/mars.test.js
@@ -15,6 +15,8 @@ describe('Mars', () => {
   })
 
   test('check apparent diameter', () => {
+    const UTCDate = new Date(Date.UTC(1992, 10, 9))
+    const jd = juliandays.getJulianDay(UTCDate)
     const apparentDiameter = Mars.getEquatorialSemiDiameter(jd)
     expect(apparentDiameter.toNumber()).toBeCloseTo(10.75 / 2) // arcsec
   })
diff --git a/tests/planets/saturn.test.js b/tests/planets/saturn.test.js
index bb13945..56a4525 100644
--- a/tests/planets/saturn.test.js
+++ b/tests/planets/saturn.test.js
@@ -4,7 +4,7 @@ describe('Saturn', () => {
   test('check magnitude', () => {
     const jd = juliandays.getJulianDay(new Date(Date.UTC(1992, 11, 20)))
     // Old formula gives -3.8. No value provided in AA for new formulae.
-    expect(Saturn.getMagnitude(jd).toNumber()).toBeCloseTo(-4.21, 1)
+    expect(Saturn.getMagnitude(jd).toNumber()).toBeCloseTo(0.74, 1)
   })
 
   test('check ring system', () => {