diff --git a/code/ryzom/client/src/interface_v3/chat_window.cpp b/code/ryzom/client/src/interface_v3/chat_window.cpp
index e74392432..1d4c0516b 100644
--- a/code/ryzom/client/src/interface_v3/chat_window.cpp
+++ b/code/ryzom/client/src/interface_v3/chat_window.cpp
@@ -604,7 +604,11 @@ void CChatGroupWindow::displayMessage(const ucstring &msg, NLMISC::CRGBA col, CC
 						pos = newmsg.find(ucstring("}"));;
 						prefix += " ";
 					}
-					newmsg = newmsg.substr(0, pos + 1) + prefix + newmsg.substr(pos + 1);
+					
+					if (pos == ucstring::npos)
+						newmsg = prefix + newmsg;
+					else
+						newmsg = newmsg.substr(0, pos + 1) + prefix + newmsg.substr(pos + 1);
 
 					// Add dynchannel number and optionally name before text if user channel
 					CCDBNodeLeaf* node = NLGUI::CDBManager::getInstance()->getDbProp("UI:SAVE:CHAT:SHOW_DYN_CHANNEL_NAME_IN_CHAT_CB", false);
@@ -615,7 +619,11 @@ void CChatGroupWindow::displayMessage(const ucstring &msg, NLMISC::CRGBA col, CC
 						STRING_MANAGER::CStringManagerClient::instance()->getDynString(textId, title);
 						prefix = title.empty() ? ucstring("") : ucstring(" ") + title;
 						pos = newmsg.find(ucstring("] "));
-						newmsg = newmsg.substr(0, pos) + prefix + newmsg.substr(pos);
+
+						if (pos == ucstring::npos)
+							newmsg = prefix + newmsg;
+						else
+							newmsg = newmsg.substr(0, pos) + prefix + newmsg.substr(pos);
 					}
 				}
 				break;