diff --git a/trim.c b/trim.c
index 3da1e74..a9b15d6 100644
--- a/trim.c
+++ b/trim.c
@@ -75,10 +75,15 @@
 	if (!td->o.trim_percentage)
 		return 0;
 
-	r = os_random_long(&td->trim_state);
-	val = (OS_RAND_MAX / 100ULL);
-	val *= (unsigned long long) td->o.trim_percentage;
+	if (td->o.use_os_rand) {
+		r = os_random_long(&td->trim_state);
+		val = (OS_RAND_MAX / 100ULL);
+	} else {
+		r = __rand(&td->__trim_state);
+		val = (FRAND_MAX / 100ULL);
+	}
 
+	val *= (unsigned long long) td->o.trim_percentage;
 	return r <= val;
 }
 #endif