diff --git a/lib/elixir/lib/base.ex b/lib/elixir/lib/base.ex
index a3c1f50dcb8..0d13460a308 100644
--- a/lib/elixir/lib/base.ex
+++ b/lib/elixir/lib/base.ex
@@ -657,10 +657,7 @@ defmodule Base do
   @spec valid64?(binary, ignore: :whitespace, padding: boolean) :: boolean
   def valid64?(string, opts \\ []) when is_binary(string) do
     pad? = Keyword.get(opts, :padding, true)
-    string |> remove_ignored(opts[:ignore]) |> validate64base!(pad?)
-    true
-  rescue
-    ArgumentError -> false
+    string |> remove_ignored(opts[:ignore]) |> validate64base?(pad?)
   end
 
   @doc """
@@ -754,110 +751,124 @@ defmodule Base do
   @spec url_valid64?(binary, ignore: :whitespace, padding: boolean) :: boolean
   def url_valid64?(string, opts \\ []) when is_binary(string) do
     pad? = Keyword.get(opts, :padding, true)
-    string |> remove_ignored(opts[:ignore]) |> validate64url!(pad?)
-    true
-  rescue
-    ArgumentError -> false
+    string |> remove_ignored(opts[:ignore]) |> validate64url?(pad?)
   end
 
   for {base, alphabet} <- [base: b64_alphabet, url: b64url_alphabet] do
     decode_name = :"decode64#{base}!"
-    validate_name = :"validate64#{base}!"
+
+    validate_name = :"validate64#{base}?"
+    validate_main_name = :"validate_main64#{validate_name}?"
+    valid_char_name = :"valid_char64#{base}?"
     {min, decoded} = alphabet |> Enum.with_index() |> to_decode_list.()
 
-    defp unquote(validate_name)(<<>>, _pad?) do
-      true
+    defp unquote(validate_main_name)(<<>>), do: true
+
+    defp unquote(validate_main_name)(
+           <<c1::8, c2::8, c3::8, c4::8, c5::8, c6::8, c7::8, c8::8, rest::binary>>
+         ) do
+      unquote(valid_char_name)(c1) and
+        unquote(valid_char_name)(c2) and
+        unquote(valid_char_name)(c3) and
+        unquote(valid_char_name)(c4) and
+        unquote(valid_char_name)(c5) and
+        unquote(valid_char_name)(c6) and
+        unquote(valid_char_name)(c7) and
+        unquote(valid_char_name)(c8) and
+        unquote(validate_main_name)(rest)
     end
 
+    defp unquote(validate_name)(<<>>, _pad?), do: true
+
     defp unquote(validate_name)(string, pad?) do
       segs = div(byte_size(string) + 7, 8) - 1
       <<main::size(^segs)-binary-unit(64), rest::binary>> = string
-
-      for <<c1::8, c2::8, c3::8, c4::8, c5::8, c6::8, c7::8, c8::8 <- main>> do
-        unquote(decode_name)(c1)
-        unquote(decode_name)(c2)
-        unquote(decode_name)(c3)
-        unquote(decode_name)(c4)
-        unquote(decode_name)(c5)
-        unquote(decode_name)(c6)
-        unquote(decode_name)(c7)
-        unquote(decode_name)(c8)
-      end
+      main_valid? = unquote(validate_main_name)(main)
 
       case rest do
+        _ when not main_valid? ->
+          false
+
         <<c1::8, c2::8, ?=, ?=>> ->
-          unquote(decode_name)(c1)
-          unquote(decode_name)(c2)
+          unquote(valid_char_name)(c1) and
+            unquote(valid_char_name)(c2)
 
         <<c1::8, c2::8, c3::8, ?=>> ->
-          unquote(decode_name)(c1)
-          unquote(decode_name)(c2)
-          unquote(decode_name)(c3)
+          unquote(valid_char_name)(c1) and
+            unquote(valid_char_name)(c2) and
+            unquote(valid_char_name)(c3)
 
         <<c1::8, c2::8, c3::8, c4::8>> ->
-          unquote(decode_name)(c1)
-          unquote(decode_name)(c2)
-          unquote(decode_name)(c3)
-          unquote(decode_name)(c4)
+          unquote(valid_char_name)(c1) and
+            unquote(valid_char_name)(c2) and
+            unquote(valid_char_name)(c3) and
+            unquote(valid_char_name)(c4)
 
         <<c1::8, c2::8, c3::8, c4::8, c5::8, c6::8, ?=, ?=>> ->
-          unquote(decode_name)(c1)
-          unquote(decode_name)(c2)
-          unquote(decode_name)(c3)
-          unquote(decode_name)(c4)
-          unquote(decode_name)(c5)
-          unquote(decode_name)(c6)
+          unquote(valid_char_name)(c1) and
+            unquote(valid_char_name)(c2) and
+            unquote(valid_char_name)(c3) and
+            unquote(valid_char_name)(c4) and
+            unquote(valid_char_name)(c5) and
+            unquote(valid_char_name)(c6)
 
         <<c1::8, c2::8, c3::8, c4::8, c5::8, c6::8, c7::8, ?=>> ->
-          unquote(decode_name)(c1)
-          unquote(decode_name)(c2)
-          unquote(decode_name)(c3)
-          unquote(decode_name)(c4)
-          unquote(decode_name)(c5)
-          unquote(decode_name)(c6)
-          unquote(decode_name)(c7)
+          unquote(valid_char_name)(c1) and
+            unquote(valid_char_name)(c2) and
+            unquote(valid_char_name)(c3) and
+            unquote(valid_char_name)(c4) and
+            unquote(valid_char_name)(c5) and
+            unquote(valid_char_name)(c6) and
+            unquote(valid_char_name)(c7)
 
         <<c1::8, c2::8, c3::8, c4::8, c5::8, c6::8, c7::8, c8::8>> ->
-          unquote(decode_name)(c1)
-          unquote(decode_name)(c2)
-          unquote(decode_name)(c3)
-          unquote(decode_name)(c4)
-          unquote(decode_name)(c5)
-          unquote(decode_name)(c6)
-          unquote(decode_name)(c7)
-          unquote(decode_name)(c8)
+          unquote(valid_char_name)(c1) and
+            unquote(valid_char_name)(c2) and
+            unquote(valid_char_name)(c3) and
+            unquote(valid_char_name)(c4) and
+            unquote(valid_char_name)(c5) and
+            unquote(valid_char_name)(c6) and
+            unquote(valid_char_name)(c7) and
+            unquote(valid_char_name)(c8)
 
         <<c1::8, c2::8>> when not pad? ->
-          unquote(decode_name)(c1)
-          unquote(decode_name)(c2)
+          unquote(valid_char_name)(c1) and
+            unquote(valid_char_name)(c2)
 
         <<c1::8, c2::8, c3::8>> when not pad? ->
-          unquote(decode_name)(c1)
-          unquote(decode_name)(c2)
-          unquote(decode_name)(c3)
+          unquote(valid_char_name)(c1) and
+            unquote(valid_char_name)(c2) and
+            unquote(valid_char_name)(c3)
 
         <<c1::8, c2::8, c3::8, c4::8, c5::8, c6::8>> when not pad? ->
-          unquote(decode_name)(c1)
-          unquote(decode_name)(c2)
-          unquote(decode_name)(c3)
-          unquote(decode_name)(c4)
-          unquote(decode_name)(c5)
-          unquote(decode_name)(c6)
+          unquote(valid_char_name)(c1) and
+            unquote(valid_char_name)(c2) and
+            unquote(valid_char_name)(c3) and
+            unquote(valid_char_name)(c4) and
+            unquote(valid_char_name)(c5) and
+            unquote(valid_char_name)(c6)
 
         <<c1::8, c2::8, c3::8, c4::8, c5::8, c6::8, c7::8>> when not pad? ->
-          unquote(decode_name)(c1)
-          unquote(decode_name)(c2)
-          unquote(decode_name)(c3)
-          unquote(decode_name)(c4)
-          unquote(decode_name)(c5)
-          unquote(decode_name)(c6)
-          unquote(decode_name)(c7)
+          unquote(valid_char_name)(c1) and
+            unquote(valid_char_name)(c2) and
+            unquote(valid_char_name)(c3) and
+            unquote(valid_char_name)(c4) and
+            unquote(valid_char_name)(c5) and
+            unquote(valid_char_name)(c6) and
+            unquote(valid_char_name)(c7)
 
         _ ->
-          raise ArgumentError, "incorrect padding"
+          false
       end
     end
 
+    @compile {:inline, [{valid_char_name, 1}]}
+    defp unquote(valid_char_name)(char)
+         when elem({unquote_splicing(decoded)}, char - unquote(min)) != nil,
+         do: true
+
+    defp unquote(valid_char_name)(_char), do: false
+
     defp unquote(decode_name)(char) do
       index = char - unquote(min)