diff --git a/trim.c b/trim.c
index a9b15d6..de792dc 100644
--- a/trim.c
+++ b/trim.c
@@ -70,7 +70,7 @@
 int io_u_should_trim(struct thread_data *td, struct io_u *io_u)
 {
 	unsigned long long val;
-	long r;
+	unsigned long r;
 
 	if (!td->o.trim_percentage)
 		return 0;