diff --git a/lib/elixir/lib/kernel/utils.ex b/lib/elixir/lib/kernel/utils.ex
index 2535a31aaac..09307ce274a 100644
--- a/lib/elixir/lib/kernel/utils.ex
+++ b/lib/elixir/lib/kernel/utils.ex
@@ -348,16 +348,19 @@ defmodule Kernel.Utils do
 
   # Finds every reference to `refs` in `guard` and wraps them in an unquote.
   defp unquote_every_ref(guard, refs) do
-    Macro.postwalk(guard, fn
-      {ref, meta, context} = var when is_atom(ref) and is_atom(context) ->
-        case {ref, var_context(meta, context)} in refs do
-          true -> literal_unquote(var)
-          false -> var
-        end
+    Macro.update_meta(
+      Macro.postwalk(guard, fn
+        {ref, meta, context} = var when is_atom(ref) and is_atom(context) ->
+          case {ref, var_context(meta, context)} in refs do
+            true -> literal_unquote(var)
+            false -> var
+          end
 
-      node ->
-        node
-    end)
+        node ->
+          node
+      end),
+      &([generated: true] ++ &1)
+    )
   end
 
   # Prefaces `guard` with unquoted versions of `refs`.
diff --git a/lib/elixir/lib/module/types/pattern.ex b/lib/elixir/lib/module/types/pattern.ex
index 36d2d25a1c2..0f713a8d455 100644
--- a/lib/elixir/lib/module/types/pattern.ex
+++ b/lib/elixir/lib/module/types/pattern.ex
@@ -183,12 +183,29 @@ defmodule Module.Types.Pattern do
   Refines the type variables in the typing context using type check guards
   such as `is_integer/1`.
   """
-  def of_guard(expr, expected, %{context: stack_context} = stack, context)
-      when stack_context != :pattern do
+  def of_guard({_, meta, _} = expr, expected, stack, context) do
+    if meta[:generated] do
+      {:ok, :dynamic, context}
+    else
+      do_of_guard(expr, expected, stack, context)
+    end
+  end
+
+  def of_guard(expr, expected, stack, context) do
+    do_of_guard(expr, expected, stack, context)
+  end
+
+  defp do_of_guard(expr, expected, %{context: stack_context} = stack, context)
+       when stack_context != :pattern do
     of_guard(expr, expected, %{stack | context: :pattern}, context)
   end
 
-  def of_guard({{:., _, [:erlang, :andalso]}, _, [left, right]} = expr, _expected, stack, context) do
+  defp do_of_guard(
+         {{:., _, [:erlang, :andalso]}, _, [left, right]} = expr,
+         _expected,
+         stack,
+         context
+       ) do
     stack = push_expr_stack(expr, stack)
 
     with {:ok, left_type, context} <- of_guard(left, @boolean, stack, context),
@@ -197,7 +214,12 @@ defmodule Module.Types.Pattern do
          do: {:ok, to_union([@boolean, right_type], context), context}
   end
 
-  def of_guard({{:., _, [:erlang, :orelse]}, _, [left, right]} = expr, _expected, stack, context) do
+  defp do_of_guard(
+         {{:., _, [:erlang, :orelse]}, _, [left, right]} = expr,
+         _expected,
+         stack,
+         context
+       ) do
     stack = push_expr_stack(expr, stack)
     left_indexes = collect_var_indexes_from_expr(left, context)
     right_indexes = collect_var_indexes_from_expr(right, context)
@@ -220,41 +242,41 @@ defmodule Module.Types.Pattern do
   # The unary operators + and - are special cased to avoid common warnings until
   # we add support for intersection types for the guard functions
   # -integer / +integer
-  def of_guard({{:., _, [:erlang, guard]}, _, [integer]}, _expected, _stack, context)
-      when guard in [:+, :-] and is_integer(integer) do
+  defp do_of_guard({{:., _, [:erlang, guard]}, _, [integer]}, _expected, _stack, context)
+       when guard in [:+, :-] and is_integer(integer) do
     {:ok, :integer, context}
   end
 
   # -float / +float
-  def of_guard({{:., _, [:erlang, guard]}, _, [float]}, _expected, _stack, context)
-      when guard in [:+, :-] and is_float(float) do
+  defp do_of_guard({{:., _, [:erlang, guard]}, _, [float]}, _expected, _stack, context)
+       when guard in [:+, :-] and is_float(float) do
     {:ok, :float, context}
   end
 
   # tuple_size(arg) == integer
-  def of_guard(
-        {{:., _, [:erlang, :==]}, _, [{{:., _, [:erlang, :tuple_size]}, _, [var]}, size]} = expr,
-        expected,
-        stack,
-        context
-      )
-      when is_var(var) and is_integer(size) do
+  defp do_of_guard(
+         {{:., _, [:erlang, :==]}, _, [{{:., _, [:erlang, :tuple_size]}, _, [var]}, size]} = expr,
+         expected,
+         stack,
+         context
+       )
+       when is_var(var) and is_integer(size) do
     of_tuple_size(var, size, expr, expected, stack, context)
   end
 
   # integer == tuple_size(arg)
-  def of_guard(
-        {{:., _, [:erlang, :==]}, _, [size, {{:., _, [:erlang, :tuple_size]}, _, [var]}]} = expr,
-        expected,
-        stack,
-        context
-      )
-      when is_var(var) and is_integer(size) do
+  defp do_of_guard(
+         {{:., _, [:erlang, :==]}, _, [size, {{:., _, [:erlang, :tuple_size]}, _, [var]}]} = expr,
+         expected,
+         stack,
+         context
+       )
+       when is_var(var) and is_integer(size) do
     of_tuple_size(var, size, expr, expected, stack, context)
   end
 
   # fun(args)
-  def of_guard({{:., _, [:erlang, guard]}, _, args} = expr, expected, stack, context) do
+  defp do_of_guard({{:., _, [:erlang, guard]}, _, args} = expr, expected, stack, context) do
     type_guard? = type_guard?(guard)
     {consider_type_guards?, keep_guarded?} = stack.type_guards
     signature = guard_signature(guard, length(args))
@@ -296,16 +318,16 @@ defmodule Module.Types.Pattern do
   end
 
   # map.field
-  def of_guard({{:., meta1, [map, field]}, meta2, []}, expected, stack, context) do
+  defp do_of_guard({{:., meta1, [map, field]}, meta2, []}, expected, stack, context) do
     of_guard({{:., meta1, [:erlang, :map_get]}, meta2, [field, map]}, expected, stack, context)
   end
 
   # var
-  def of_guard(var, _expected, _stack, context) when is_var(var) do
+  defp do_of_guard(var, _expected, _stack, context) when is_var(var) do
     {:ok, get_var!(var, context), context}
   end
 
-  def of_guard(expr, _expected, stack, context) do
+  defp do_of_guard(expr, _expected, stack, context) do
     of_shared(expr, stack, context, &of_guard(&1, :dynamic, &2, &3))
   end
 
diff --git a/lib/elixir/test/elixir/module/types/types_test.exs b/lib/elixir/test/elixir/module/types/types_test.exs
index d03ee0e28a0..1b2ba91fa30 100644
--- a/lib/elixir/test/elixir/module/types/types_test.exs
+++ b/lib/elixir/test/elixir/module/types/types_test.exs
@@ -213,6 +213,21 @@ defmodule Module.Types.TypesTest do
       assert string == :none
     end
 
+    defguard tuple_or_nil(term) when is_tuple(term) or is_nil(term)
+
+    test "does not warn on guards defined with defguard" do
+      string =
+        warning(
+          [var],
+          [is_atom(var)],
+          case var do
+            _ when tuple_or_nil(var) -> :ok
+          end
+        )
+
+      assert string == :none
+    end
+
     test "check body" do
       string = warning([x], [is_integer(x)], :foo = x)