diff --git a/rtgui/toolpanelcoord.cc b/rtgui/toolpanelcoord.cc
index cacbee99d..7920b7a9b 100644
--- a/rtgui/toolpanelcoord.cc
+++ b/rtgui/toolpanelcoord.cc
@@ -311,6 +311,7 @@ ToolPanelCoordinator::~ToolPanelCoordinator ()
 
 void ToolPanelCoordinator::imageTypeChanged(bool isRaw, bool isBayer, bool isXtrans)
 {
+    GThreadLock lock;
 
     if(isRaw) {
         rawPanelSW->set_sensitive(true);