diff --git a/fishctl/src/config/server.rs b/fishctl/src/config/server.rs
index 7cf4903..e0491bf 100644
--- a/fishctl/src/config/server.rs
+++ b/fishctl/src/config/server.rs
@@ -172,7 +172,10 @@ fn validate_emoji(value: &str) -> Result<(), ValidationError> {
     // check if `value` is a custom emoji
     // "+", "-", "_" are allowed in emoji shortcodes in Misskey variants
     // ref: <https://github.com/misskey-dev/mfm.js/blob/6aaf68089023c6adebe44123eebbc4dcd75955e0/docs/syntax.md?plain=1#L583>
-    if value.len() > 2 {
+    if value.is_ascii() && value.len() > 2 {
+        if value.chars().nth(0).unwrap() != ':' || value.chars().last().unwrap() != ':' {
+            return error;
+        }
         if value[1..value.len() - 1]
             .chars()
             .all(|c| c.is_ascii_alphanumeric() || c == '+' || c == '-' || c == '_')
@@ -183,3 +186,31 @@ fn validate_emoji(value: &str) -> Result<(), ValidationError> {
 
     error
 }
+
+#[cfg(test)]
+mod test {
+    #[test]
+    fn validate_emoji() {
+        super::validate_emoji("⭐").unwrap();
+        super::validate_emoji("👍").unwrap();
+        super::validate_emoji("❤️").unwrap();
+        super::validate_emoji("💜").unwrap();
+        super::validate_emoji("🧛🏽").unwrap();
+        super::validate_emoji("🧑‍🤝‍🧑").unwrap();
+        super::validate_emoji(":ameow_attention:").unwrap();
+        super::validate_emoji(":meow_peek:").unwrap();
+        super::validate_emoji(":ABlobcatLonglong:").unwrap();
+        super::validate_emoji(":ABlobcat++Longlong:").unwrap();
+        super::validate_emoji(":ABlobcat-Longlong:").unwrap();
+
+        super::validate_emoji("⭐⭐").unwrap_err();
+        super::validate_emoji("::").unwrap_err();
+        super::validate_emoji("?").unwrap_err();
+        super::validate_emoji(":?:").unwrap_err();
+        super::validate_emoji(":ameow_attention：").unwrap_err();
+        super::validate_emoji("").unwrap_err();
+        super::validate_emoji("ABlobcat-Longlong:").unwrap_err();
+        super::validate_emoji("ABlobcat-Longlong").unwrap_err();
+        super::validate_emoji(":雨:").unwrap_err();
+    }
+}