diff --git a/lib/sympto/index.js b/lib/sympto/index.js
index f93ecac..48e1980 100644
--- a/lib/sympto/index.js
+++ b/lib/sympto/index.js
@@ -107,14 +107,14 @@ function throwIfArgsAreNotInRequiredFormat(cycles) {
     assert.ok(cycle.length > 0) //what about 2 cycles of 1 day each?!
     assert.ok(cycle[0].bleeding !== null)
     assert.equal(typeof cycle[0].bleeding, 'object', "First cycle day must contain bleeding value")
-    assert.equal(typeof cycle[0].bleeding.value, 'number')
+    assert.equal(typeof cycle[0].bleeding.value, 'number', "Bleeding value must be a number")
     cycle.forEach(day => {
       assert.equal(typeof day.date, 'string')
       assert.doesNotThrow(() => LocalDate.parse(day.date))
-      if (day.temperature) assert.equal(typeof day.temperature.value, 'number')
-      if (day.mucus) assert.equal(typeof day.mucus.value, 'number')
-      if (day.mucus) assert.ok(day.mucus.value >= 0)
-      if (day.mucus) assert.ok(day.mucus.value < 5)
+      if (day.temperature) assert.equal(typeof day.temperature.value, 'number', "temperature value must be number")
+      if (day.mucus) assert.equal(typeof day.mucus.value, 'number', "mucus value must be number")
+      if (day.mucus) assert.ok(day.mucus.value >= 0, "mucus value must be 0 or bigger")
+      if (day.mucus) assert.ok(day.mucus.value <= 4, "mucus value must be 4 or smaller")
       if (day.cervix) assert.equal(typeof day.cervix.value, 'object')
       if (day.cervix) assert.ok(day.cervix.value.opening >= 0, "cervix opening value must be 0 or bigger")
       if (day.cervix) assert.ok(day.cervix.value.opening <= 2, "cervix opening value must be 2 or smaller")