diff --git a/source/index.ts b/source/index.ts
index 34148f5..6deb8d0 100644
--- a/source/index.ts
+++ b/source/index.ts
@@ -250,7 +250,7 @@ is.urlString = (value: unknown): value is string => {
 // Example: `is.truthy = (value: unknown): value is (not false | not 0 | not '' | not undefined | not null) => Boolean(value);`
 is.truthy = <T>(value: T | Falsy): value is T => Boolean(value);
 // Example: `is.falsy = (value: unknown): value is (not true | 0 | '' | undefined | null) => Boolean(value);`
-is.falsy = (value: unknown) => !value;
+is.falsy = <T>(value: T | Falsy): value is Falsy => !value;
 
 is.nan = (value: unknown) => Number.isNaN(value as number);