diff --git a/rtdata/languages/default b/rtdata/languages/default
index b17eb315a..4a5dfe1c5 100644
--- a/rtdata/languages/default
+++ b/rtdata/languages/default
@@ -2303,6 +2303,7 @@ TP_LOCALLAB_BLMETHOD_TOOLTIP;Normal - direct blur and noise with all settings.\n
 TP_LOCALLAB_BLNORM;Normal
 TP_LOCALLAB_BLSYM;Symmetric
 TP_LOCALLAB_BLWH;All changes forced in Black and White
+TP_LOCALLAB_BLWH_TOOLTIP;Force color change composante "a" and "b" to zero. 
 TP_LOCALLAB_SPOTNAME;New Spot
 TP_LOCALLAB_BLUFR;Smooth - Blur - Grain - Denoise
 TP_LOCALLAB_BLUMETHOD_TOOLTIP;To blur the background and isolate the foreground:\n*Blur the background by a RT-spot fully covering the image (high values for scope and transition) - normal or inverse.\n*Isolate the foreground by one or more excluding RT-spot with the tools you want (increse scope), you can use a mask to enhance and amplify the effects.\n\nThis module can be used in additional noise reduction,including "median" and "Guided filter" 
diff --git a/rtgui/controlspotpanel.cc b/rtgui/controlspotpanel.cc
index e7e4b3203..f9a532ec5 100644
--- a/rtgui/controlspotpanel.cc
+++ b/rtgui/controlspotpanel.cc
@@ -346,6 +346,9 @@ ControlSpotPanel::ControlSpotPanel():
     if (complexsoft < 2) {
         artifBox->pack_start(*thresh_);
     }
+    if (showtooltip) {
+        blwh_->set_tooltip_text(M("TP_LOCALLAB_BLWH_TOOLTIP"));
+    }
 
     artifBox->pack_start(*iter_);
     artifBox->pack_start(*balan_);