diff --git a/packages/next-safe-action/src/adapters/types.ts b/packages/next-safe-action/src/adapters/types.ts
index 23e9dc85..12a8e6c7 100644
--- a/packages/next-safe-action/src/adapters/types.ts
+++ b/packages/next-safe-action/src/adapters/types.ts
@@ -1,23 +1,23 @@
 import type { GenericSchema, GenericSchemaAsync, InferInput, InferOutput } from "valibot";
 import type { z } from "zod";
 
-export type Exists<T> = any extends T ? never : T;
+export type IfInstalled<T> = any extends T ? never : T;
 
-export type Schema = Exists<z.ZodType> | Exists<GenericSchema> | Exists<GenericSchemaAsync>;
+export type Schema = IfInstalled<z.ZodType> | IfInstalled<GenericSchema> | IfInstalled<GenericSchemaAsync>;
 export type Infer<S extends Schema> =
-	S extends Exists<z.ZodType>
+	S extends IfInstalled<z.ZodType>
 		? z.infer<S>
-		: S extends Exists<GenericSchema>
+		: S extends IfInstalled<GenericSchema>
 			? InferOutput<S>
-			: S extends Exists<GenericSchemaAsync>
+			: S extends IfInstalled<GenericSchemaAsync>
 				? InferOutput<S>
 				: never;
 export type InferIn<S extends Schema> =
-	S extends Exists<z.ZodType>
+	S extends IfInstalled<z.ZodType>
 		? z.input<S>
-		: S extends Exists<GenericSchema>
+		: S extends IfInstalled<GenericSchema>
 			? InferInput<S>
-			: S extends Exists<GenericSchemaAsync>
+			: S extends IfInstalled<GenericSchemaAsync>
 				? InferInput<S>
 				: never;
 export type InferArray<BAS extends readonly Schema[]> = {
@@ -39,12 +39,12 @@ export interface ValidationAdapter {
 		data: unknown
 	): Promise<{ success: true; data: Infer<S> } | { success: false; issues: ValidationIssue[] }>;
 	// zod
-	validate<S extends z.ZodType>(
+	validate<S extends IfInstalled<z.ZodType>>(
 		schema: S,
 		data: unknown
 	): Promise<{ success: true; data: Infer<S> } | { success: false; issues: ValidationIssue[] }>;
 	// valibot
-	validate<S extends GenericSchema | GenericSchemaAsync>(
+	validate<S extends IfInstalled<GenericSchema | GenericSchemaAsync>>(
 		schema: S,
 		data: unknown
 	): Promise<{ success: true; data: Infer<S> } | { success: false; issues: ValidationIssue[] }>;
diff --git a/packages/next-safe-action/src/adapters/valibot.ts b/packages/next-safe-action/src/adapters/valibot.ts
index 016cc72a..dad8ab7d 100644
--- a/packages/next-safe-action/src/adapters/valibot.ts
+++ b/packages/next-safe-action/src/adapters/valibot.ts
@@ -1,8 +1,8 @@
 import { getDotPath, safeParseAsync, type GenericSchema, type GenericSchemaAsync } from "valibot";
-import type { Infer, ValidationAdapter } from "./types";
+import type { IfInstalled, Infer, ValidationAdapter } from "./types";
 
 class ValibotAdapter implements ValidationAdapter {
-	async validate<S extends GenericSchema | GenericSchemaAsync>(schema: S, data: unknown) {
+	async validate<S extends IfInstalled<GenericSchema | GenericSchemaAsync>>(schema: S, data: unknown) {
 		const result = await safeParseAsync(schema, data);
 
 		if (result.success) {
diff --git a/packages/next-safe-action/src/adapters/zod.ts b/packages/next-safe-action/src/adapters/zod.ts
index 70442c40..cf49dcae 100644
--- a/packages/next-safe-action/src/adapters/zod.ts
+++ b/packages/next-safe-action/src/adapters/zod.ts
@@ -1,10 +1,10 @@
 import type { z } from "zod";
-import type { Infer, ValidationAdapter } from "./types";
+import type { IfInstalled, Infer, ValidationAdapter } from "./types";
 
 export type ZodSchema = z.ZodType;
 
 class ZodAdapter implements ValidationAdapter {
-	async validate<S extends z.ZodType>(schema: S, data: unknown) {
+	async validate<S extends IfInstalled<z.ZodType>>(schema: S, data: unknown) {
 		const result = await schema.safeParseAsync(data);
 
 		if (result.success) {