diff --git a/.changes/api-isTauri-type.md b/.changes/api-isTauri-type.md
new file mode 100644
index 000000000..22422f0c6
--- /dev/null
+++ b/.changes/api-isTauri-type.md
@@ -0,0 +1,5 @@
+---
+"@tauri-apps/api": "patch:bug"
+---
+
+Fix `isTauri` incorrect return type. 
\ No newline at end of file
diff --git a/tooling/api/src/core.ts b/tooling/api/src/core.ts
index e6a92e2a3..9beca856d 100644
--- a/tooling/api/src/core.ts
+++ b/tooling/api/src/core.ts
@@ -238,8 +238,8 @@ export class Resource {
   }
 }
 
-function isTauri() {
-  return 'isTauri' in window && window.isTauri
+function isTauri(): boolean {
+  return 'isTauri' in window && !!window.isTauri
 }
 
 export type { InvokeArgs, InvokeOptions }