diff --git a/src/components/trait/forms/LabelValueRow.vue b/src/components/trait/forms/LabelValueRow.vue
index 0cc46ac08..98c4d1f33 100644
--- a/src/components/trait/forms/LabelValueRow.vue
+++ b/src/components/trait/forms/LabelValueRow.vue
@@ -38,6 +38,7 @@
             <BasicInputField
                 v-bind:field-name="'Category'"
                 v-bind:show-label="false"
+                v-bind:field-help="canBeRemoved ? undefined : 'Ordinal scales require at least two categories'"
                 v-bind:placeholder="categoryPlaceholder"
                 v-bind:value="label"
                 v-on:input="$emit('label-change', $event)"
diff --git a/src/components/trait/forms/ValueRow.vue b/src/components/trait/forms/ValueRow.vue
index 0965ec860..88c48d4d1 100644
--- a/src/components/trait/forms/ValueRow.vue
+++ b/src/components/trait/forms/ValueRow.vue
@@ -22,6 +22,7 @@
         <BasicInputField
             v-bind:field-name="'Category'"
             v-bind:show-label="false"
+            v-bind:field-help="canBeRemoved ? undefined : 'Nominal scales require at least one category'"
             v-bind:placeholder="valuePlaceholder"
             v-bind:value="value"
             v-on:input="$emit('value-change', $event)"