diff --git a/src/gettext.erl b/src/gettext.erl
index ba2b562..3b5b6e7 100644
--- a/src/gettext.erl
+++ b/src/gettext.erl
@@ -64,10 +64,10 @@ recreate_db(Server) ->
 
 %%--------------------------------------------------------------------
 
-store_pofile(Lang, File) when binary(File) ->
+store_pofile(Lang, File) when is_binary(File) ->
     store_pofile(?DEFAULT_SERVER, Lang, File).
 
-store_pofile(Server, Lang, File) when binary(File) ->
+store_pofile(Server, Lang, File) when is_binary(File) ->
     gen_server:call(Server, {store_pofile, Lang, File}, infinity).
 
 %%--------------------------------------------------------------------
@@ -153,10 +153,10 @@ eat_more([$"|T], Acc)  -> eat_string(T, Acc);
 eat_more(T, Acc)       -> {lists:reverse(Acc), T}.
 
 
-to_list(A) when atom(A)    -> atom_to_list(A);
-to_list(I) when integer(I) -> integer_to_list(I);
-to_list(B) when binary(B)  -> binary_to_list(B);
-to_list(L) when list(L)    -> L.
+to_list(A) when is_atom(A)    -> atom_to_list(A);
+to_list(I) when is_integer(I) -> integer_to_list(I);
+to_list(B) when is_binary(B)  -> binary_to_list(B);
+to_list(L) when is_list(L)    -> L.
 
 
 %%% --------------------------------------------------------------------
diff --git a/src/gettext_compile.erl b/src/gettext_compile.erl
index 629328f..001e502 100644
--- a/src/gettext_compile.erl
+++ b/src/gettext_compile.erl
@@ -201,7 +201,7 @@ pt(Form, Opts) ->
     put(fname, ""),
     pt(Form, Opts, undefined).
 
-pt([H|T],Opts,Func) when list(H) ->
+pt([H|T],Opts,Func) when is_list(H) ->
     ?debug( "--- 1 --- ~p~n",[H]),
     F = fun (X) -> pt(X,Opts,Func) end,
     [lists:map(F,H)|pt(T,Opts,Func)];
@@ -237,7 +237,7 @@ pt([{block,N,B}|T], Opts, Func) ->
     Block = {block,N,pt(B,Opts,Func)},
     [Block|pt(T, Opts, Func)];
 %%%
-pt([H|T], Opts, Func) when tuple(H) ->
+pt([H|T], Opts, Func) when is_tuple(H) ->
     ?debug( "--- 3 --- ~p~n",[H]),
     [while(size(H), H, Opts, Func) | pt(T, Opts, Func)];
 %%%
@@ -245,7 +245,7 @@ pt([H|T], Opts, Func) ->
     ?debug( "--- 4 --- ~p~n",[H]),
     [H | pt(T, Opts, Func)];
 %%%
-pt(T, Opts, Func) when tuple(T) ->
+pt(T, Opts, Func) when is_tuple(T) ->
     ?debug( "--- 5 --- ~p~n",[T]),
     while(size(T), T, Opts, Func);
 %%%
@@ -305,10 +305,10 @@ open_po_file(Gettext_App_Name, GtxtDir, DefLang) ->
 close_file() ->
     file:close(get(fd)).
 
-to_list(A) when atom(A)    -> atom_to_list(A);
-to_list(I) when integer(I) -> integer_to_list(I);
-to_list(B) when binary(B)  -> binary_to_list(B);
-to_list(L) when list(L)    -> L.
+to_list(A) when is_atom(A)    -> atom_to_list(A);
+to_list(I) when is_integer(I) -> integer_to_list(I);
+to_list(B) when is_binary(B)  -> binary_to_list(B);
+to_list(L) when is_list(L)    -> L.
 
 
 
diff --git a/src/gettext_server.erl b/src/gettext_server.erl
index b674e14..df3267c 100644
--- a/src/gettext_server.erl
+++ b/src/gettext_server.erl
@@ -120,7 +120,7 @@ get_gettext_dir(CallBackMod) ->
     case os:getenv("GETTEXT_DIR") of
 	false -> 
 	    case catch CallBackMod:gettext_dir() of
-		Dir when list(Dir) -> Dir;
+		Dir when is_list(Dir) -> Dir;
 		_                  -> code:priv_dir(gettext) % fallback
 	    end;
 	Dir   -> Dir