diff --git a/crates/hyfetch/src/models.rs b/crates/hyfetch/src/models.rs
index 6487acf8..ad6962d6 100644
--- a/crates/hyfetch/src/models.rs
+++ b/crates/hyfetch/src/models.rs
@@ -1,10 +1,10 @@
-use std::collections::{HashMap};
+use std::collections::HashMap;
 
 use anyhow::{Context as _, Result};
 use serde::{Deserialize, Serialize};
 
-use crate::color_util::Lightness;
 use crate::color_profile::ColorProfile;
+use crate::color_util::Lightness;
 use crate::neofetch_util::ColorAlignment;
 use crate::types::{AnsiMode, Backend, TerminalTheme};
 
@@ -26,8 +26,6 @@ pub struct Config {
     pub custom_presets: Option<HashMap<String, Vec<String>>>,
 }
 
-
-
 impl Config {
     pub fn default_lightness(theme: TerminalTheme) -> Lightness {
         match theme {
@@ -44,6 +42,9 @@ impl Config {
         let mut profiles = HashMap::new();
         if let Some(custom_presets) = &self.custom_presets {
             for (preset_name, colors) in custom_presets {
+                if preset_name == "random" {
+                    return Err(anyhow::anyhow!("custom preset key `random` is reserved"));
+                }
                 let color_profile = build_hex_color_profile(colors).with_context(|| {
                     format!("failed to validate custom preset key `{preset_name}`")
                 })?;
@@ -55,10 +56,15 @@ impl Config {
 }
 
 pub fn build_hex_color_profile(hex_colors: &[String]) -> Result<ColorProfile> {
+    if hex_colors.is_empty() {
+        return Err(anyhow::anyhow!("hex color list cannot be empty"));
+    }
+
     for color in hex_colors {
-        if !color.starts_with('#') ||
-            (color.len() != 4 && color.len() != 7) ||
-            !color[1..].chars().all(|c| c.is_ascii_hexdigit()) {
+        if !color.starts_with('#')
+            || (color.len() != 4 && color.len() != 7)
+            || !color[1..].chars().all(|c| c.is_ascii_hexdigit())
+        {
             return Err(anyhow::anyhow!("invalid hex color: {color}"));
         }
     }
diff --git a/hyfetch/main.py b/hyfetch/main.py
index 6052f650..83d0b4f3 100755
--- a/hyfetch/main.py
+++ b/hyfetch/main.py
@@ -491,7 +491,7 @@ def run():
         if '#' in preset_string:
             colors = [s.strip() for s in preset_string.split(',')]
             return build_hex_color_profile(colors)
-        
+
         preset_profiles: dict[str, ColorProfile] = {
             name: preset for name, preset in PRESETS.items()
         }
@@ -511,7 +511,7 @@ def run():
         raise ValueError(
             "PRESET should be comma-separated hex colors or one of "
             f"{{{','.join(available)}}}"
-    )
+        )
 
     try:
         preset = parse_preset_string(config.preset, config)
diff --git a/hyfetch/models.py b/hyfetch/models.py
index 5a55e537..34da3d07 100644
--- a/hyfetch/models.py
+++ b/hyfetch/models.py
@@ -10,6 +10,9 @@ from .types import AnsiMode, LightDark, BackendLiteral
 
 
 def build_hex_color_profile(hex_colors: list[str]) -> ColorProfile:
+    if not hex_colors:
+        raise ValueError('hex color list cannot be empty')
+
     for color in hex_colors:
         if not (
             color.startswith('#')
@@ -48,6 +51,8 @@ class Config:
         profiles: dict[str, ColorProfile] = {}
         if self.custom_presets:
             for preset_name, colors in self.custom_presets.items():
+                if preset_name == 'random':
+                    raise ValueError('custom preset key "random" is reserved')
                 try:
                     profiles[preset_name] = build_hex_color_profile(colors)
                 except ValueError as err: