diff --git a/src/rebar_utils.erl b/src/rebar_utils.erl
index a04798e..aa29364 100644
--- a/src/rebar_utils.erl
+++ b/src/rebar_utils.erl
@@ -34,6 +34,8 @@
          sh_send/3,
          find_files/2,
          find_files/3,
+         find_files_by_ext/2,
+         find_files_by_ext/3,
          now_str/0,
          ensure_dir/1,
          beam_to_mod/2,
@@ -160,6 +162,28 @@ find_files(Dir, Regex, Recursive) ->
     filelib:fold_files(Dir, Regex, Recursive,
                        fun(F, Acc) -> [F | Acc] end, []).
 
+%% Find files by extension, for example ".erl", avoiding resource fork
+%% files in OS X.  Such files are named for example src/._xyz.erl
+%% Such files may also appear with network filesystems on OS X.
+%%
+%% The Ext is really a regexp, with any leading dot implicitly
+%% escaped, and anchored at the end of the string.
+%%
+find_files_by_ext(Dir, Ext) ->
+    find_files_by_ext(Dir, Ext, true).
+
+find_files_by_ext(Dir, Ext, Recursive) ->
+    %% Convert simple extension to proper regex
+    EscapeDot = case Ext of
+                    "." ++ _ ->
+                        "\\";
+                    _ ->
+                        %% allow for other suffixes, such as _pb.erl
+                        ""
+                end,
+    ExtRe = "^[^._].*" ++ EscapeDot ++ Ext ++ [$$],
+    find_files(Dir, ExtRe, Recursive).
+
 now_str() ->
     {{Year, Month, Day}, {Hour, Minute, Second}} = calendar:local_time(),
     lists:flatten(io_lib:format("~4b/~2..0b/~2..0b ~2..0b:~2..0b:~2..0b",