diff --git a/.config/fish/functions/latex-color.fish b/.config/fish/functions/latex-color.fish
index 4a5a885..3e31259 100644
--- a/.config/fish/functions/latex-color.fish
+++ b/.config/fish/functions/latex-color.fish
@@ -18,23 +18,24 @@ function latex-color --description "Get the LaTeX color from HEX code"
         set hex (string sub -s 2 $hex)
     end
 
-    # Check if the length of the hex is valid
-    if not contains $(string length $hex) $(string split " " "3 4 6 8")
-        echo "Error: Invalid HEX code"
+    # Check if the hex code is valid
+    if not string match -qir '^[0-9A-F]{3,8}$' $hex
+       and not contains $(string length $hex) $(string split " " "3 4 6 8")
+        echo "Error: Invalid HEX code" 1>&2
         return 1
     end
 
-    # Expand 3 hex to 4 hex
+    # Expand 3 to 4
     if test (string length $hex) -eq 3
         set hex $(string join "" $hex 0)
     end
 
-    # Expand 4 hex to 8 hex
+    # Expand 4 to 8
     if test (string length $hex) -eq 4
         set hex "$(string replace -ar '(.)' '$1$1' $hex)00"
     end
 
-    # Expand 6 hex to 8 hex
+    # Expand 6 to 8
     if test (string length $hex) -eq 6
         set hex $(string join "" $hex 00)
     end