diff --git a/src/builders/ZodSchemaClassBuilder.ts b/src/builders/ZodSchemaClassBuilder.ts
index fe12b66..52e6dbd 100644
--- a/src/builders/ZodSchemaClassBuilder.ts
+++ b/src/builders/ZodSchemaClassBuilder.ts
@@ -18,25 +18,32 @@ extends TraitExpressionBuilder<Superclass, Traits> {
     declare ["constructor"]: typeof ZodSchemaClassBuilder
 
     schema<
-        Super             extends AbstractClass<object, []> & { schema?: never, defaultValues?: never },
+        Super                              extends AbstractClass<object, []> & { schema?: never, schemaWithDefaultValues?: never },
 
-        SchemaT           extends z.ZodRawShape,
-        SchemaUnknownKeys extends z.UnknownKeysParam,
-        SchemaCatchall    extends z.ZodTypeAny,
+        SchemaT                            extends z.ZodRawShape,
+        SchemaUnknownKeys                  extends z.UnknownKeysParam,
+        SchemaCatchall                     extends z.ZodTypeAny,
 
-        Values            extends object,
-        DefaultValues     extends Partial<Values>,
+        SchemaWithDefaultValuesT           extends z.ZodRawShape,
+        SchemaWithDefaultValuesUnknownKeys extends z.UnknownKeysParam,
+        SchemaWithDefaultValuesCatchall    extends z.ZodTypeAny,
+
+        Values                             extends object,
+        PartialValues                      extends Partial<Values>,
     >(
         this: ZodSchemaClassBuilder<Super, Traits>,
 
-        { schema, defaultValues }: {
-            schema:         z.ZodObject<SchemaT, SchemaUnknownKeys, SchemaCatchall, Values, Values>
-            defaultValues:  DefaultValues
+        props: {
+            schema: z.ZodObject<SchemaT, SchemaUnknownKeys, SchemaCatchall, Values, Values>
+
+            schemaWithDefaultValues: (
+                schema: z.ZodObject<SchemaT, SchemaUnknownKeys, SchemaCatchall, Values, Values>
+            ) => z.ZodObject<SchemaWithDefaultValuesT, SchemaWithDefaultValuesUnknownKeys, SchemaWithDefaultValuesCatchall, Values, PartialValues>
         },
     ) {
         class Schemas extends (this.expressionSuperclass as AbstractClass<object, []>) {
-            static readonly schema        = schema
-            static readonly defaultValues = defaultValues
+            static readonly schema                  = props.schema
+            static readonly schemaWithDefaultValues = props.schemaWithDefaultValues(props.schema)
 
             constructor(values: Values) {
                 super()
@@ -63,29 +70,33 @@ extends TraitExpressionBuilder<Superclass, Traits> {
     }
 
     jsonifiable<
-        Super                      extends ZodSchemaAbstractClass<Instance, SchemaT, SchemaUnknownKeys, SchemaCatchall, Values, DefaultValues>
+        Super                              extends ZodSchemaAbstractClass<Instance, SchemaT, SchemaUnknownKeys, SchemaCatchall, SchemaWithDefaultValuesT, SchemaWithDefaultValuesUnknownKeys, SchemaWithDefaultValuesCatchall, Values, PartialValues>
                                          & { jsonifySchema?: never, dejsonifySchema?: never },
-        Instance                   extends Values,
+        Instance                           extends Values,
 
-        SchemaT                    extends z.ZodRawShape,
-        SchemaUnknownKeys          extends z.UnknownKeysParam,
-        SchemaCatchall             extends z.ZodTypeAny,
+        SchemaT                            extends z.ZodRawShape,
+        SchemaUnknownKeys                  extends z.UnknownKeysParam,
+        SchemaCatchall                     extends z.ZodTypeAny,
 
-        Values                     extends object,
-        DefaultValues              extends Partial<Values>,
+        SchemaWithDefaultValuesT           extends z.ZodRawShape,
+        SchemaWithDefaultValuesUnknownKeys extends z.UnknownKeysParam,
+        SchemaWithDefaultValuesCatchall    extends z.ZodTypeAny,
 
-        JsonifySchemaT             extends z.ZodRawShape,
-        JsonifySchemaUnknownKeys   extends z.UnknownKeysParam,
-        JsonifySchemaCatchall      extends z.ZodTypeAny,
+        Values                             extends object,
+        PartialValues                      extends Partial<Values>,
 
-        DejsonifySchemaT           extends z.ZodRawShape,
-        DejsonifySchemaUnknownKeys extends z.UnknownKeysParam,
-        DejsonifySchemaCatchall    extends z.ZodTypeAny,
+        JsonifySchemaT                     extends z.ZodRawShape,
+        JsonifySchemaUnknownKeys           extends z.UnknownKeysParam,
+        JsonifySchemaCatchall              extends z.ZodTypeAny,
 
-        JsonifiedValues            extends JsonifiableObject,
+        DejsonifySchemaT                   extends z.ZodRawShape,
+        DejsonifySchemaUnknownKeys         extends z.UnknownKeysParam,
+        DejsonifySchemaCatchall            extends z.ZodTypeAny,
+
+        JsonifiedValues                    extends JsonifiableObject,
     >(
         this: ZodSchemaClassBuilder<
-            Super | ZodSchemaAbstractClass<Instance, SchemaT, SchemaUnknownKeys, SchemaCatchall, Values, DefaultValues>,
+            Super | ZodSchemaAbstractClass<Instance, SchemaT, SchemaUnknownKeys, SchemaCatchall, SchemaWithDefaultValuesT, SchemaWithDefaultValuesUnknownKeys, SchemaWithDefaultValuesCatchall, Values, PartialValues>,
             Traits
         >,
 
@@ -115,7 +126,7 @@ extends TraitExpressionBuilder<Superclass, Traits> {
                     Instance & JsonifiableSchemas,
 
                     // TODO: for some reason, ConstructorParameters<Super> does not work here. Maybe try to find a fix?
-                    ConstructorParameters<ZodSchemaAbstractClass<Instance, SchemaT, SchemaUnknownKeys, SchemaCatchall, Values, DefaultValues>>
+                    ConstructorParameters<ZodSchemaAbstractClass<Instance, SchemaT, SchemaUnknownKeys, SchemaCatchall, SchemaWithDefaultValuesT, SchemaWithDefaultValuesUnknownKeys, SchemaWithDefaultValuesCatchall, Values, PartialValues>>
                 > &
                 StaticMembers<Super> &
                 StaticMembers<typeof JsonifiableSchemas>
diff --git a/src/shapes/ZodSchemaClass.ts b/src/shapes/ZodSchemaClass.ts
index 0b33a2d..680c59a 100644
--- a/src/shapes/ZodSchemaClass.ts
+++ b/src/shapes/ZodSchemaClass.ts
@@ -3,41 +3,53 @@ import { z } from "zod"
 
 
 export type ZodSchemaClass<
-    Instance          extends Values,
+    Instance                           extends Values,
 
-    SchemaT           extends z.ZodRawShape,
-    SchemaUnknownKeys extends z.UnknownKeysParam,
-    SchemaCatchall    extends z.ZodTypeAny,
+    SchemaT                            extends z.ZodRawShape,
+    SchemaUnknownKeys                  extends z.UnknownKeysParam,
+    SchemaCatchall                     extends z.ZodTypeAny,
 
-    Values            extends object,
-    DefaultValues     extends Partial<Values>,
+    SchemaWithDefaultValuesT           extends z.ZodRawShape,
+    SchemaWithDefaultValuesUnknownKeys extends z.UnknownKeysParam,
+    SchemaWithDefaultValuesCatchall    extends z.ZodTypeAny,
+
+    Values                             extends object,
+    PartialValues                      extends Partial<Values>,
 > = (
     Class<Instance, [values: Values]> &
-    ZodSchemas<SchemaT, SchemaUnknownKeys, SchemaCatchall, Values, DefaultValues>
+    ZodSchemas<SchemaT, SchemaUnknownKeys, SchemaCatchall, SchemaWithDefaultValuesT, SchemaWithDefaultValuesUnknownKeys, SchemaWithDefaultValuesCatchall, Values, PartialValues>
 )
 
 export type ZodSchemaAbstractClass<
-    Instance          extends Values,
+    Instance                           extends Values,
 
-    SchemaT           extends z.ZodRawShape,
-    SchemaUnknownKeys extends z.UnknownKeysParam,
-    SchemaCatchall    extends z.ZodTypeAny,
+    SchemaT                            extends z.ZodRawShape,
+    SchemaUnknownKeys                  extends z.UnknownKeysParam,
+    SchemaCatchall                     extends z.ZodTypeAny,
 
-    Values            extends object,
-    DefaultValues     extends Partial<Values>,
+    SchemaWithDefaultValuesT           extends z.ZodRawShape,
+    SchemaWithDefaultValuesUnknownKeys extends z.UnknownKeysParam,
+    SchemaWithDefaultValuesCatchall    extends z.ZodTypeAny,
+
+    Values                             extends object,
+    PartialValues                      extends Partial<Values>,
 > = (
     AbstractClass<Instance, [values: Values]> &
-    ZodSchemas<SchemaT, SchemaUnknownKeys, SchemaCatchall, Values, DefaultValues>
+    ZodSchemas<SchemaT, SchemaUnknownKeys, SchemaCatchall, SchemaWithDefaultValuesT, SchemaWithDefaultValuesUnknownKeys, SchemaWithDefaultValuesCatchall, Values, PartialValues>
 )
 
 export type ZodSchemas<
-    SchemaT           extends z.ZodRawShape,
-    SchemaUnknownKeys extends z.UnknownKeysParam,
-    SchemaCatchall    extends z.ZodTypeAny,
+    SchemaT                            extends z.ZodRawShape,
+    SchemaUnknownKeys                  extends z.UnknownKeysParam,
+    SchemaCatchall                     extends z.ZodTypeAny,
 
-    Values            extends object,
-    DefaultValues     extends Partial<Values>,
+    SchemaWithDefaultValuesT           extends z.ZodRawShape,
+    SchemaWithDefaultValuesUnknownKeys extends z.UnknownKeysParam,
+    SchemaWithDefaultValuesCatchall    extends z.ZodTypeAny,
+
+    Values                             extends object,
+    PartialValues                      extends Partial<Values>,
 > = {
-    readonly schema:         z.ZodObject<SchemaT, SchemaUnknownKeys, SchemaCatchall, Values, Values>
-    readonly defaultValues:  DefaultValues
+    readonly schema:                   z.ZodObject<SchemaT, SchemaUnknownKeys, SchemaCatchall, Values, Values>
+    readonly schemaWithDefaultValues:  z.ZodObject<SchemaWithDefaultValuesT, SchemaWithDefaultValuesUnknownKeys, SchemaWithDefaultValuesCatchall, Values, PartialValues>
 }
diff --git a/src/tests.ts b/src/tests.ts
index 3a392ad..ddcafe7 100644
--- a/src/tests.ts
+++ b/src/tests.ts
@@ -3,7 +3,6 @@ import { z } from "zod"
 import { zodSchemaClass } from "./builders/ZodSchemaClassBuilder"
 import { dejsonify, jsonify } from "./schema/jsonify"
 import { MobXObservableZodSchemaObject } from "./traits/MobXObservableZodSchemaObject"
-import { StaticMembers } from "./util"
 
 
 const exp = zodSchemaClass
@@ -16,7 +15,9 @@ const exp = zodSchemaClass
             name: z.string(),
         }),
 
-        defaultValues: { id: -1n },
+        schemaWithDefaultValues: s => s.extend({
+            id: s.shape.id.default(-1n)
+        }),
     })
     .jsonifiable({
         jsonifySchema: s => s.extend({
@@ -33,7 +34,12 @@ const exp = zodSchemaClass
 @exp.staticImplements
 class User extends exp.extends implements Implements<typeof exp> {}
 
-User.defaultValues
+const test = User.schema.extend({
+    prout: z.string()
+}).merge(
+    User.schemaWithDefaultValues
+)
+
 const inst = User.create({ id: 1n, name: "" })
 // console.log(inst)
 const jsonifiedUser = await inst.jsonifyPromise()
diff --git a/src/traits/ExtendableZodSchemaObject.ts b/src/traits/ExtendableZodSchemaObject.ts
index 243e1b4..2b232fb 100644
--- a/src/traits/ExtendableZodSchemaObject.ts
+++ b/src/traits/ExtendableZodSchemaObject.ts
@@ -6,7 +6,7 @@ import { ZodSchemaClass } from "../shapes/ZodSchemaClass"
 export const ExtendableZodSchemaObject = trait
     .implement(Super => class ExtendableZodSchemaObject extends Super {
         static extend<
-            Self extends ZodSchemaClass<any, any, any, any, any, any>,
+            Self extends ZodSchemaClass<any, any, any, any, any, any, any, any, any>,
         >(
             this: Self
         ) {
diff --git a/src/traits/InstantiableZodSchemaObject.ts b/src/traits/InstantiableZodSchemaObject.ts
index d567034..9b70483 100644
--- a/src/traits/InstantiableZodSchemaObject.ts
+++ b/src/traits/InstantiableZodSchemaObject.ts
@@ -1,5 +1,5 @@
 import { trait } from "@thilawyn/traitify-ts"
-import { Effect, pipe } from "effect"
+import { Effect } from "effect"
 import { HasRequiredKeys } from "type-fest"
 import { z } from "zod"
 import { ZodSchemaClass } from "../shapes/ZodSchemaClass"
@@ -29,70 +29,67 @@ type NewZodSchemaInstanceArgs<Input extends object> = (
 export const InstantiableZodSchemaObject = trait
     .implement(Super => class InstantiableZodSchemaObject extends Super {
         static create<
-            Instance          extends Values,
+            Instance                           extends Values,
 
-            SchemaT           extends z.ZodRawShape,
-            SchemaUnknownKeys extends z.UnknownKeysParam,
-            SchemaCatchall    extends z.ZodTypeAny,
+            SchemaT                            extends z.ZodRawShape,
+            SchemaUnknownKeys                  extends z.UnknownKeysParam,
+            SchemaCatchall                     extends z.ZodTypeAny,
 
-            Values            extends object,
-            DefaultValues     extends Partial<Values>,
+            SchemaWithDefaultValuesT           extends z.ZodRawShape,
+            SchemaWithDefaultValuesUnknownKeys extends z.UnknownKeysParam,
+            SchemaWithDefaultValuesCatchall    extends z.ZodTypeAny,
+
+            Values                             extends object,
+            PartialValues                      extends Partial<Values>,
         >(
-            this: ZodSchemaClass<Instance, SchemaT, SchemaUnknownKeys, SchemaCatchall, Values, DefaultValues>,
-
-            ...[values, params]: NewZodSchemaInstanceArgs<
-                NewZodSchemaInstanceInput<Values, DefaultValues>
-            >
+            this: ZodSchemaClass<Instance, SchemaT, SchemaUnknownKeys, SchemaCatchall, SchemaWithDefaultValuesT, SchemaWithDefaultValuesUnknownKeys, SchemaWithDefaultValuesCatchall, Values, PartialValues>,
+            ...[values, params]: NewZodSchemaInstanceArgs<PartialValues>
         ) {
             return new this(
-                this.schema.parse({ ...this.defaultValues, ...values }, params)
+                this.schemaWithDefaultValues.parse(values, params)
             )
         }
 
         static async createPromise<
-            Instance          extends Values,
+            Instance                           extends Values,
 
-            SchemaT           extends z.ZodRawShape,
-            SchemaUnknownKeys extends z.UnknownKeysParam,
-            SchemaCatchall    extends z.ZodTypeAny,
+            SchemaT                            extends z.ZodRawShape,
+            SchemaUnknownKeys                  extends z.UnknownKeysParam,
+            SchemaCatchall                     extends z.ZodTypeAny,
 
-            Values            extends object,
-            DefaultValues     extends Partial<Values>,
+            SchemaWithDefaultValuesT           extends z.ZodRawShape,
+            SchemaWithDefaultValuesUnknownKeys extends z.UnknownKeysParam,
+            SchemaWithDefaultValuesCatchall    extends z.ZodTypeAny,
+
+            Values                             extends object,
+            PartialValues                      extends Partial<Values>,
         >(
-            this: ZodSchemaClass<Instance, SchemaT, SchemaUnknownKeys, SchemaCatchall, Values, DefaultValues>,
-
-            ...[values, params]: NewZodSchemaInstanceArgs<
-                NewZodSchemaInstanceInput<Values, DefaultValues>
-            >
+            this: ZodSchemaClass<Instance, SchemaT, SchemaUnknownKeys, SchemaCatchall, SchemaWithDefaultValuesT, SchemaWithDefaultValuesUnknownKeys, SchemaWithDefaultValuesCatchall, Values, PartialValues>,
+            ...[values, params]: NewZodSchemaInstanceArgs<PartialValues>
         ) {
             return new this(
-                await this.schema.parseAsync({ ...this.defaultValues, ...values }, params)
+                await this.schemaWithDefaultValues.parseAsync(values, params)
             )
         }
 
         static createEffect<
-            Instance          extends Values,
+            Instance                           extends Values,
 
-            SchemaT           extends z.ZodRawShape,
-            SchemaUnknownKeys extends z.UnknownKeysParam,
-            SchemaCatchall    extends z.ZodTypeAny,
+            SchemaT                            extends z.ZodRawShape,
+            SchemaUnknownKeys                  extends z.UnknownKeysParam,
+            SchemaCatchall                     extends z.ZodTypeAny,
 
-            Values            extends object,
-            DefaultValues     extends Partial<Values>,
+            SchemaWithDefaultValuesT           extends z.ZodRawShape,
+            SchemaWithDefaultValuesUnknownKeys extends z.UnknownKeysParam,
+            SchemaWithDefaultValuesCatchall    extends z.ZodTypeAny,
+
+            Values                             extends object,
+            PartialValues                      extends Partial<Values>,
         >(
-            this: ZodSchemaClass<Instance, SchemaT, SchemaUnknownKeys, SchemaCatchall, Values, DefaultValues>,
-
-            ...[values, params]: NewZodSchemaInstanceArgs<
-                NewZodSchemaInstanceInput<Values, DefaultValues>
-            >
+            this: ZodSchemaClass<Instance, SchemaT, SchemaUnknownKeys, SchemaCatchall, SchemaWithDefaultValuesT, SchemaWithDefaultValuesUnknownKeys, SchemaWithDefaultValuesCatchall, Values, PartialValues>,
+            ...[values, params]: NewZodSchemaInstanceArgs<PartialValues>
         ) {
-            return pipe(
-                parseZodTypeEffect(
-                    this.schema,
-                    { ...this.defaultValues, ...values },
-                    params,
-                ),
-
+            return parseZodTypeEffect(this.schemaWithDefaultValues, values, params).pipe(
                 Effect.map(values => new this(values)),
             )
         }