diff --git a/lib/fun_with_flags/ui/utils.ex b/lib/fun_with_flags/ui/utils.ex
index 087596a..7eea49d 100644
--- a/lib/fun_with_flags/ui/utils.ex
+++ b/lib/fun_with_flags/ui/utils.ex
@@ -160,17 +160,19 @@ defmodule FunWithFlags.UI.Utils do
 
   def validate(name) do
     string = to_string(name)
+
     cond do
       blank?(string) ->
         {:fail, "can't be blank"}
-      String.match?(string, ~r/\?/) ->
-        {:fail, "includes invalid characters: '?'"}
+
+      string |> String.to_charlist() |> Enum.any?(&URI.char_reserved?/1) ->
+        {:fail, "includes URI reserved characters"}
+
       true ->
         :ok
     end
   end
 
-
   def parse_and_validate_float(string) do
     if blank?(string) do
       {:fail, "can't be blank"}
diff --git a/test/fun_with_flags/ui/utils_test.exs b/test/fun_with_flags/ui/utils_test.exs
index 742a966..b769f49 100644
--- a/test/fun_with_flags/ui/utils_test.exs
+++ b/test/fun_with_flags/ui/utils_test.exs
@@ -200,21 +200,22 @@ defmodule FunWithFlags.UI.UtilsTest do
     end
   end
 
-
   describe "sanitize(name)" do
     test "it removes leading and trailing whitespace" do
       assert "apricot" = Utils.sanitize(" apricot   ")
     end
   end
 
-
   describe "validate(name)" do
     test "it returns {:fail, reason} for blank values" do
       assert {:fail, "can't be blank"} = Utils.validate(:"")
     end
 
-    test "it returns {:fail, reason} for values with question marks" do
-      assert {:fail, "includes invalid characters: '?'"} = Utils.validate(:banana?)
+    test "it returns {:fail, reason} for values with URI reserved characters" do
+      assert {:fail, "includes URI reserved characters"} = Utils.validate(:banana?)
+      assert {:fail, "includes URI reserved characters"} = Utils.validate(:"ban/ana")
+      assert {:fail, "includes URI reserved characters"} = Utils.validate(:"ban#ana")
+      assert {:fail, "includes URI reserved characters"} = Utils.validate(:"ban&ana")
     end
 
     test "it returns :ok otherwise" do