diff --git a/color-module/src/lib.rs b/color-module/src/lib.rs
index e2ce429..f619430 100644
--- a/color-module/src/lib.rs
+++ b/color-module/src/lib.rs
@@ -283,13 +283,13 @@ pub fn series(
     let oklch = Oklch::from_color(origin_color.clone());
 
     let mut color_series = Vec::new();
-    for s in expand_amount..1 {
+    for s in expand_amount..=1 {
         let darkened_color = oklch.darken(s as f32 * step);
         let srgb = Srgb::from_color(darkened_color);
         color_series.push(format!("{:x}", srgb.into_format::<u8>()));
     }
     color_series.push(format!("{:x}", origin_color.into_format::<u8>()));
-    for s in 1..expand_amount {
+    for s in 1..=expand_amount {
         let lightened_color = oklch.lighten(s as f32 * step);
         let srgb = Srgb::from_color(lightened_color);
         color_series.push(format!("{:x}", srgb.into_format::<u8>()));