diff --git a/.changeset/little-sloths-punch.md b/.changeset/little-sloths-punch.md
new file mode 100644
index 000000000..9ee43cd65
--- /dev/null
+++ b/.changeset/little-sloths-punch.md
@@ -0,0 +1,5 @@
+---
+'@lion/ui': patch
+---
+
+[form-core] make sure that slots with property fallbacks ignore initialization updates (undefined on firstUpdated). See https://stackblitz.com/edit/vitejs-vite-encdg2xd?file=lion-demo.js
diff --git a/packages/ui/components/form-core/src/FormControlMixin.js b/packages/ui/components/form-core/src/FormControlMixin.js
index 25227f010..e2af48ebe 100644
--- a/packages/ui/components/form-core/src/FormControlMixin.js
+++ b/packages/ui/components/form-core/src/FormControlMixin.js
@@ -293,11 +293,11 @@ const FormControlMixinImplementation = superclass =>
         );
       }
 
-      if (changedProperties.has('label') && this._labelNode) {
+      if (changedProperties.has('label') && this.__label && this._labelNode) {
         this._labelNode.textContent = this.label;
       }
 
-      if (changedProperties.has('helpText') && this._helpTextNode) {
+      if (changedProperties.has('helpText') && this.__helpText && this._helpTextNode) {
         this._helpTextNode.textContent = this.helpText;
       }
 
diff --git a/packages/ui/components/form-core/test/FormControlMixin.test.js b/packages/ui/components/form-core/test/FormControlMixin.test.js
index 940b4956d..cae68ad51 100644
--- a/packages/ui/components/form-core/test/FormControlMixin.test.js
+++ b/packages/ui/components/form-core/test/FormControlMixin.test.js
@@ -52,11 +52,13 @@ describe('FormControlMixin', () => {
       const elElem = /** @type {FormControlMixinClass} */ (
         await fixture(html`
         <${tag}>
-          <label slot="label">Email address</label>
+          <label slot="label"><b>Email</b> address</label>
           ${inputSlot}
         </${tag}>`)
       );
       expect(elElem.label).to.equal('Email address', 'as an element');
+      // @ts-expect-error
+      expect(elElem._labelNode.innerHTML).to.equal('<b>Email</b> address', 'html as an element');
     });
 
     it('has a label that supports inner html', async () => {
@@ -68,6 +70,8 @@ describe('FormControlMixin', () => {
         </${tag}>`)
       );
       expect(el.label).to.equal('Email address');
+      // @ts-expect-error
+      expect(el._labelNode.innerHTML).to.equal('Email <span>address</span>');
     });
 
     it('only takes label of direct child', async () => {
@@ -139,11 +143,13 @@ describe('FormControlMixin', () => {
       const elElem = /** @type {FormControlMixinClass} */ (
         await fixture(html`
         <${tag}>
-          <div slot="help-text">We will not send you any spam</div>
+          <div slot="help-text">We will <b>not</b> send you any spam</div>
           ${inputSlot}
         </${tag}>`)
       );
       expect(elElem.helpText).to.equal('We will not send you any spam', 'as an element');
+      // @ts-expect-error
+      expect(elElem._helpTextNode.innerHTML).to.equal('We will <b>not</b> send you any spam');
     });
 
     it('can have a help-text that supports inner html', async () => {
@@ -155,6 +161,8 @@ describe('FormControlMixin', () => {
         </${tag}>`)
       );
       expect(el.helpText).to.equal('We will not send you any spam');
+      // @ts-expect-error
+      expect(el._helpTextNode.innerHTML).to.equal('We will not send you any <span>spam</span>');
     });
 
     it('only takes help-text of direct child', async () => {