diff --git a/src/schema/decimal.ts b/src/schema/decimal.ts
new file mode 100644
index 0000000..cb16e42
--- /dev/null
+++ b/src/schema/decimal.ts
@@ -0,0 +1,5 @@
+import Decimal from "decimal.js"
+import { z } from "zod"
+
+
+export const decimal = z.custom<Decimal>(v => Decimal.isDecimal(v))
diff --git a/src/schema/jsonified/bigint.ts b/src/schema/jsonified/bigint.ts
index 4627b45..6266dd5 100644
--- a/src/schema/jsonified/bigint.ts
+++ b/src/schema/jsonified/bigint.ts
@@ -6,11 +6,11 @@ import { z } from "zod"
 export type JsonifiedBigInt = Opaque<string, "@thilawyn/zod-schema-class/JsonifiedBigInt">
 
 
-export function jsonifyBigIntSchema<S extends z.ZodBigInt>(schema: S) {
+export function jsonifyBigIntSchema<S extends z.ZodType<bigint>>(schema: S) {
     return schema.transform(v => v.toString() as JsonifiedBigInt)
 }
 
-export function dejsonifyBigIntSchema<S extends z.ZodBigInt>(schema: S) {
+export function dejsonifyBigIntSchema<S extends z.ZodType<bigint>>(schema: S) {
     return z
         .custom<JsonifiedBigInt>(identity)
         .pipe(
diff --git a/src/schema/jsonified/date.ts b/src/schema/jsonified/date.ts
index 1524456..ff4d0a1 100644
--- a/src/schema/jsonified/date.ts
+++ b/src/schema/jsonified/date.ts
@@ -6,11 +6,11 @@ import { z } from "zod"
 export type JsonifiedDate = Opaque<string, "@thilawyn/zod-schema-class/JsonifiedDate">
 
 
-export function jsonifyDateSchema<S extends z.ZodDate>(schema: S) {
+export function jsonifyDateSchema<S extends z.ZodType<Date>>(schema: S) {
     return schema.transform(v => v.toString() as JsonifiedDate)
 }
 
-export function dejsonifyDateSchema<S extends z.ZodDate>(schema: S) {
+export function dejsonifyDateSchema<S extends z.ZodType<Date>>(schema: S) {
     return z
         .custom<JsonifiedDate>(identity)
         .pipe(
diff --git a/src/schema/jsonified/decimal.ts b/src/schema/jsonified/decimal.ts
index 2aacd7a..eb500a6 100644
--- a/src/schema/jsonified/decimal.ts
+++ b/src/schema/jsonified/decimal.ts
@@ -7,15 +7,11 @@ import { z } from "zod"
 export type JsonifiedDecimal = Opaque<string, "@thilawyn/zod-schema-class/JsonifiedDecimal">
 
 
-export function jsonifyDecimalSchema<
-    S extends z.ZodType<Decimal, z.ZodTypeDef, Decimal>
->(schema: S) {
+export function jsonifyDecimalSchema<S extends z.ZodType<Decimal>>(schema: S) {
     return schema.transform(v => v.toJSON() as JsonifiedDecimal)
 }
 
-export function dejsonifyDecimalSchema<
-    S extends z.ZodType<Decimal, z.ZodTypeDef, Decimal>
->(schema: S) {
+export function dejsonifyDecimalSchema<S extends z.ZodType<Decimal>>(schema: S) {
     return z
         .custom<JsonifiedDecimal>(identity)
         .pipe(
diff --git a/src/schema/lib.ts b/src/schema/lib.ts
index b7c00ae..0ab38cb 100644
--- a/src/schema/lib.ts
+++ b/src/schema/lib.ts
@@ -1,2 +1,3 @@
+export * from "./decimal"
 export * from "./effect"
 export * from "./jsonified"