diff --git a/lib/elixir/lib/exception.ex b/lib/elixir/lib/exception.ex
index 3347c250e85..7837372f5b0 100644
--- a/lib/elixir/lib/exception.ex
+++ b/lib/elixir/lib/exception.ex
@@ -640,8 +640,26 @@ defmodule UndefinedFunctionError do
   end
 
   def message(%{reason: :"module could not be loaded", module: module, function: function, arity: arity}) do
+    suffix =
+      case :code.get_object_code(module) do
+        {_, _, path} ->
+          case :beam_lib.info(path) do
+            info when is_list(info) ->
+              alt_module = Keyword.get(info, :module)
+              exports = exports_for(alt_module)
+              if {function, arity} in exports do
+                ". Did you mean:\n\n      * " <>
+                  Exception.format_mfa(alt_module, function, arity) <> "\n"
+              else
+                ". Did you mean #{inspect alt_module}?"
+              end
+            _ -> ""
+          end
+        _ -> ""
+      end
     "function " <> Exception.format_mfa(module, function, arity) <>
-      " is undefined (module #{inspect module} is not available)"
+      " is undefined (module #{inspect module} is not available)" <>
+      suffix
   end
 
   def message(%{reason: :"function not exported",  module: module, function: function, arity: arity, exports: exports}) do
diff --git a/lib/elixir/test/elixir/exception_test.exs b/lib/elixir/test/elixir/exception_test.exs
index 3da381289c8..ad8257447c2 100644
--- a/lib/elixir/test/elixir/exception_test.exs
+++ b/lib/elixir/test/elixir/exception_test.exs
@@ -387,6 +387,13 @@ defmodule ExceptionTest do
                  * get_cookie/0
                  * set_cookie/2
            """
+    assert %UndefinedFunctionError{module: Genserver, function: :start_link, arity: 3} |> message == """
+           function Genserver.start_link/3 is undefined (module Genserver is not available). Did you mean:
+
+                 * GenServer.start_link/3
+           """
+    assert %UndefinedFunctionError{module: Genserver, function: :start_link, arity: 1} |> message ==
+           "function Genserver.start_link/1 is undefined (module Genserver is not available). Did you mean GenServer?"
   end
 
   test "UndefinedFunctionError when the mfa is a macro but require wasn't called" do
diff --git a/lib/mix/lib/mix/tasks/xref.ex b/lib/mix/lib/mix/tasks/xref.ex
index 92373188382..4b0d5fd00ba 100644
--- a/lib/mix/lib/mix/tasks/xref.ex
+++ b/lib/mix/lib/mix/tasks/xref.ex
@@ -240,8 +240,12 @@ defmodule Mix.Tasks.Xref do
   end
 
   defp format_warning(file, {lines, :unknown_module, module, function, arity, _}) do
-    ["function ", Exception.format_mfa(module, function, arity),
-     " is undefined (module #{inspect module} is not available)\n" | format_file_lines(file, lines)]
+    message =
+      [module: module, function: function, arity: arity, reason: :"module could not be loaded"]
+      |> UndefinedFunctionError.exception()
+      |> Exception.message()
+
+    [message, "\n" | format_file_lines(file, lines)]
   end
 
   defp format_file_lines(file, [line]) do
diff --git a/lib/mix/test/mix/tasks/xref_test.exs b/lib/mix/test/mix/tasks/xref_test.exs
index f803bc6e17f..5f3e68a5189 100644
--- a/lib/mix/test/mix/tasks/xref_test.exs
+++ b/lib/mix/test/mix/tasks/xref_test.exs
@@ -63,6 +63,21 @@ defmodule Mix.Tasks.XrefTest do
     """
   end
 
+  test "warnings: reports module case mismatch" do
+    assert_warnings """
+    defmodule A do
+      def a, do: Genserver.start_link(A, [], [])
+    end
+    """, """
+    warning: function Genserver.start_link/3 is undefined (module Genserver is not available). Did you mean:
+
+          * GenServer.start_link/3
+
+      lib/a.ex:2
+
+    """
+  end
+
   test "warnings: reports missing captures" do
     assert_warnings """
     defmodule A do