diff --git a/curses.h b/curses.h
index 8f5a89c1..19d288e1 100644
--- a/curses.h
+++ b/curses.h
@@ -1292,8 +1292,10 @@ PDCEX  bool    is_immedok(const WINDOW *);
 PDCEX  bool    is_keypad(const WINDOW *);
 PDCEX  bool    is_leaveok(const WINDOW *);
 PDCEX  bool    is_nodelay(const WINDOW *);
+PDCEX  bool    is_notimeout(const WINDOW *);
 PDCEX  bool    is_pad(const WINDOW *);
 PDCEX  bool    is_scrollok(const WINDOW *);
+PDCEX  bool    is_subwin(const WINDOW *);
 PDCEX  bool    is_syncok(const WINDOW *);
 PDCEX  int     set_tabsize(int);
 PDCEX  int     use_default_colors(void);
diff --git a/pdcurses/inopts.c b/pdcurses/inopts.c
index 6774bc8d..754c660c 100644
--- a/pdcurses/inopts.c
+++ b/pdcurses/inopts.c
@@ -34,6 +34,7 @@ inopts
 
     bool is_keypad(const WINDOW *win);
     bool is_nodelay(const WINDOW *win);
+    bool is_notimeout(const WINDOW *win);
 
 ### Description
 
@@ -101,6 +102,9 @@ inopts
 
    is_keypad() and is_nodelay() returns TRUE or FALSE.
 
+   is_notimeout() is provided for compatibility with other curses
+   implementations, i.e. it always returns FALSE.
+
 ### Portability
                              X/Open  ncurses  NetBSD
     cbreak                      Y       Y       Y
@@ -126,6 +130,7 @@ inopts
     nocrmode                    Y       Y       Y
     is_keypad                   -       Y       Y
     is_nodelay                  -       Y       -
+    is_notimeout                -       Y       -
 
 **man-end****************************************************************/
 
@@ -381,3 +386,12 @@ bool is_nodelay(const WINDOW *win)
 
     return win->_nodelay;
 }
+
+bool is_notimeout(const WINDOW *win)
+{
+    (void) win;
+
+    PDC_LOG(("is_notimeout() - called - returning FALSE...\n"));
+
+    return FALSE;
+}
diff --git a/pdcurses/window.c b/pdcurses/window.c
index 98dcc10e..26bdef18 100644
--- a/pdcurses/window.c
+++ b/pdcurses/window.c
@@ -19,6 +19,7 @@ window
     int mvwin(WINDOW *win, int y, int x);
     int mvderwin(WINDOW *win, int pary, int parx);
     int syncok(WINDOW *win, bool bf);
+    bool is_subwin(const WINDOW *win);
     bool is_syncok(const WINDOW *win);
     void wsyncup(WINDOW *win);
     void wcursyncup(WINDOW *win);
@@ -70,6 +71,9 @@ window
    If syncok() is called with a second argument of TRUE, this causes a
    wsyncup() to be called every time the window is changed.
 
+   is_subwin() reports whether the specified window is a subwindow,
+   created by subwin() or derwin().
+
    is_syncok() reports whether the specified window is in syncok mode.
 
    wcursyncup() causes the current cursor position of all of a window's
@@ -104,7 +108,7 @@ window
    syncok() return OK or ERR. wsyncup(), wcursyncup() and wsyncdown()
    return nothing.
 
-   is_syncok() returns TRUE or FALSE.
+   is_subwin() and is_syncok() returns TRUE or FALSE.
 
 ### Errors
 
@@ -126,6 +130,7 @@ window
     dupwin                      Y       Y       Y
     wsyncup                     Y       Y       Y
     syncok                      Y       Y       Y
+    is_subwin                   -       Y       -
     is_syncok                   -       Y       -
     wcursyncup                  Y       Y       Y
     wsyncdown                   Y       Y       Y
@@ -560,6 +565,16 @@ int syncok(WINDOW *win, bool bf)
     return OK;
 }
 
+bool is_subwin(const WINDOW *win)
+{
+    PDC_LOG(("is_subwin() - called\n"));
+
+    if (!win)
+        return FALSE;
+
+    return ((win->_flags & _SUBWIN) ? TRUE : FALSE);
+}
+
 bool is_syncok(const WINDOW *win)
 {
     PDC_LOG(("is_syncok() - called\n"));