diff --git a/frontend/src/components/Contributions/ContributionForm.vue b/frontend/src/components/Contributions/ContributionForm.vue
index e5e31b11c..2161306ee 100644
--- a/frontend/src/components/Contributions/ContributionForm.vue
+++ b/frontend/src/components/Contributions/ContributionForm.vue
@@ -165,7 +165,6 @@ const validationSchema = computed(() => {
       .required('form.validation.contributionMemo.required'),
     hours: string()
       .typeError({ key: 'form.validation.hours.typeError', values: { min: 0.01, max: maxHours } })
-      .required()
       .transform((currentValue) =>
         !currentValue || typeof currentValue !== 'string'
           ? currentValue
@@ -179,18 +178,22 @@ const validationSchema = computed(() => {
         return /^\d+(\.\d{0,2})?$/.test(value.toString())
       })
       // min and max are not working with string, so we need to do it manually
-      .test('min-hours', 'form.validation.hours.min', (value) => {
-        if (value === undefined || value === null || Number(value).isNaN()) {
+      .test('min-hours', { key: 'form.validation.hours.min', values: { min: 0.01 } }, (value) => {
+        if (value === undefined || value === null || Number.isNaN(parseFloat(value))) {
           return false
         }
         return parseFloat(value) >= 0.01
       })
-      .test('max-hours', 'form.validation.hours.max', (value) => {
-        if (value === undefined || value === null || Number(value).isNaN()) {
-          return false
-        }
-        return parseFloat(value) <= maxHours
-      }),
+      .test(
+        'max-hours',
+        { key: 'form.validation.hours.max', values: { max: maxHours } },
+        (value) => {
+          if (value === undefined || value === null || Number.isNaN(parseFloat(value))) {
+            return false
+          }
+          return parseFloat(value) <= maxHours
+        },
+      ),
     amount: number().min(0.01).max(maxAmounts),
   })
 })