diff --git a/minetest/colorspec.lua b/minetest/colorspec.lua
index 0536167..3658b12 100644
--- a/minetest/colorspec.lua
+++ b/minetest/colorspec.lua
@@ -185,7 +185,7 @@ function colorspec.from_string(string)
 	if number then
 		return colorspec.from_number(number * 0x100 + alpha)
 	end
-	local hex_text = string:match(hex)
+	local hex_text = string:match("^" .. hex .. "$")
 	local len, num = hex_text:len(), tonumber(hex_text, 16)
 	if len == 8 then
 		return colorspec.from_number(num)
diff --git a/persistence.lua b/persistence.lua
index a4fb408..1342a7b 100644
--- a/persistence.lua
+++ b/persistence.lua
@@ -112,7 +112,7 @@ function lua_log_file:_dump(value, is_key)
 	end
 	if _type == "string" then
 		local reference_strings = self.reference_strings
-		if is_key and ((not reference_strings) or value:len() <= key:len()) and value:match"[%a_][%a%d_]*" then
+		if is_key and ((not reference_strings) or value:len() <= key:len()) and value:match"^[%a_][%a%d_]*$" then
 			-- Short key
 			return value, true
 		end