diff --git a/src/lib.rs b/src/lib.rs
index 64efbe40..e8760a49 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -359,7 +359,7 @@ pub use crate::windows::grab as _grab;
 #[cfg(feature = "unstable_grab")]
 pub fn grab<T>(callback: T) -> Result<(), GrabError>
 where
-    T: Fn(Event) -> Option<Event> + 'static,
+    T: FnMut(Event) -> Option<Event> + 'static,
 {
     _grab(callback)
 }