diff --git a/kdecoration/breezebutton.h b/kdecoration/breezebutton.h
--- a/kdecoration/breezebutton.h
+++ b/kdecoration/breezebutton.h
@@ -88,7 +88,7 @@
         //@{
         void setOpacity( qreal value )
         {
-            if( m_opacity == value ) return;
+            if( qFuzzyIsNull( m_opacity - value ) ) return;
             m_opacity = value;
             update();
         }
diff --git a/kdecoration/breezedecoration.cpp b/kdecoration/breezedecoration.cpp
--- a/kdecoration/breezedecoration.cpp
+++ b/kdecoration/breezedecoration.cpp
@@ -94,7 +94,7 @@
     //________________________________________________________________
     void Decoration::setOpacity( qreal value )
     {
-        if( m_opacity == value ) return;
+        if( qFuzzyIsNull( m_opacity - value ) ) return;
         m_opacity = value;
         update();