diff --git a/usr.bin/ministat/ministat.c b/usr.bin/ministat/ministat.c
index 625fb329e2b..150593e5be9 100644
--- a/usr.bin/ministat/ministat.c
+++ b/usr.bin/ministat/ministat.c
@@ -208,6 +208,12 @@ static double
 Var(struct dataset *ds)
 {
 
+	/*
+	 * Due to limited precision it is possible that sy^2/n > syy,
+	 * but variance cannot actually be negative.
+	 */
+	if (ds->syy <= ds->sy * ds->sy / ds->n)
+		return (0);
 	return (ds->syy - ds->sy * ds->sy / ds->n) / (ds->n - 1.0);
 }