diff --git a/.changeset/tricky-schools-tap.md b/.changeset/tricky-schools-tap.md
new file mode 100644
index 0000000..fb81ccf
--- /dev/null
+++ b/.changeset/tricky-schools-tap.md
@@ -0,0 +1,5 @@
+---
+"@svbstrate/core": patch
+---
+
+Fix bug in `pick` where `customProperties` weren't included, plus widen `customProperties` value to `SvbstrateValue`
diff --git a/packages/core/lib/index.ts b/packages/core/lib/index.ts
index 07497c3..d05c453 100644
--- a/packages/core/lib/index.ts
+++ b/packages/core/lib/index.ts
@@ -216,7 +216,8 @@ export function pick<T = types.UnknownKeyValue>(
       theme.macros[prop as keyof types.Macros] ||
       theme.variants[prop as keyof types.Variants] ||
       theme.shorthands[prop as keyof types.Shorthands] ||
-      theme.properties[prop as keyof types.CSSProperties]
+      theme.properties[prop as keyof types.CSSProperties] ||
+      theme.customProperties[prop as keyof types.CustomProperties]
     ) {
       styles[prop] = props[prop] as types.SvbstrateStyleObject;
     } else {
diff --git a/packages/core/lib/types.ts b/packages/core/lib/types.ts
index 3f0d68b..e090ddd 100644
--- a/packages/core/lib/types.ts
+++ b/packages/core/lib/types.ts
@@ -161,7 +161,7 @@ export interface ThemeConfig {
   };
   customProperties: {
     [Property in keyof CustomProperties]: (
-      value: Value,
+      value: SvbstrateValue,
       theme: Tokens
     ) => SvbstrateStyleObject;
   };