diff --git a/gtk2_ardour/ardour_ui.cc b/gtk2_ardour/ardour_ui.cc
index 1130177fe2..5161a6626d 100644
--- a/gtk2_ardour/ardour_ui.cc
+++ b/gtk2_ardour/ardour_ui.cc
@@ -2129,7 +2129,7 @@ ARDOUR_UI::snapshot_session (bool switch_to_it)
 
 		time (&n);
 		localtime_r (&n, &local_time);
-		strftime (timebuf, sizeof(timebuf), "%FT%T", &local_time);
+		strftime (timebuf, sizeof(timebuf), "%FT%H.%M.%S", &local_time);
 		prompter.set_initial_text (timebuf);
 	}
 
@@ -2154,6 +2154,12 @@ ARDOUR_UI::snapshot_session (bool switch_to_it)
 				msg.run ();
 				goto again;
 			}
+			if (snapname.find (':') != string::npos) {
+				MessageDialog msg (_("To ensure compatibility with various systems\n"
+				                     "snapshot names may not contain a ':' character"));
+				msg.run ();
+				goto again;
+			}
 		}
 
 		vector<sys::path> p;