diff --git a/src/expr/core/src/window_function/call.rs b/src/expr/core/src/window_function/call.rs
index 663479584ddd1..797c27b963c95 100644
--- a/src/expr/core/src/window_function/call.rs
+++ b/src/expr/core/src/window_function/call.rs
@@ -78,10 +78,6 @@ impl Frame {
             exclusion,
         }
     }
-
-    pub fn is_unbounded(&self) -> bool {
-        self.bounds.is_unbounded()
-    }
 }
 
 impl Frame {
diff --git a/src/stream/src/executor/over_window/general.rs b/src/stream/src/executor/over_window/general.rs
index 4c37e31f4e1d7..9116ba9b73618 100644
--- a/src/stream/src/executor/over_window/general.rs
+++ b/src/stream/src/executor/over_window/general.rs
@@ -165,7 +165,10 @@ impl<S: StateStore> OverWindowExecutor<S> {
         let input_info = args.input.info();
         let input_schema = &input_info.schema;
 
-        let has_unbounded_frame = args.calls.iter().any(|call| call.frame.is_unbounded());
+        let has_unbounded_frame = args
+            .calls
+            .iter()
+            .any(|call| call.frame.bounds.is_unbounded());
         let cache_policy = if has_unbounded_frame {
             // For unbounded frames, we finally need all entries of the partition in the cache,
             // so for simplicity we just use full cache policy for these cases.