diff --git a/.changeset/lovely-tables-scream.md b/.changeset/lovely-tables-scream.md
new file mode 100644
index 000000000..322a73fa9
--- /dev/null
+++ b/.changeset/lovely-tables-scream.md
@@ -0,0 +1,5 @@
+---
+'@lion/form-core': patch
+---
+
+fixed css selector syntax for disabled [slot=input]'
diff --git a/packages/form-core/src/FormControlMixin.js b/packages/form-core/src/FormControlMixin.js
index 19feadbcc..a4638e765 100644
--- a/packages/form-core/src/FormControlMixin.js
+++ b/packages/form-core/src/FormControlMixin.js
@@ -684,7 +684,7 @@ const FormControlMixinImplementation = superclass =>
           }
 
           /***** {state} :disabled *****/
-          :host([disabled]) .input-group ::slotted(slot='input') {
+          :host([disabled]) .input-group ::slotted([slot='input']) {
             color: var(--disabled-text-color, #767676);
           }