diff --git a/doc/rdesktop.1 b/doc/rdesktop.1
index 215f0c7..c52955e 100644
--- a/doc/rdesktop.1
+++ b/doc/rdesktop.1
@@ -103,7 +103,7 @@ state, but might cause problems with some Xservers like Xvnc.
 .TP
 .BR "-X <windowid>"
 Embed rdesktop-window in another window. The windowid is expected to
-be decimal.
+be decimal or hexadecimal (prefixed by 0x).
 .TP
 .BR "-a <bpp>"
 Sets the colour depth for the connection (8, 15, 16 or 24).
diff --git a/rdesktop.c b/rdesktop.c
index 6010531..25b6ed0 100644
--- a/rdesktop.c
+++ b/rdesktop.c
@@ -558,7 +558,7 @@ main(int argc, char *argv[])
 				break;
 
 			case 'X':
-				g_embed_wnd = strtol(optarg, NULL, 10);
+				g_embed_wnd = strtol(optarg, NULL, 0);
 				break;
 
 			case 'a':