diff --git a/src/core/raster/qgsmultibandcolorrenderer.cpp b/src/core/raster/qgsmultibandcolorrenderer.cpp
index 9677dd10bd6..58fd6a3f6cd 100644
--- a/src/core/raster/qgsmultibandcolorrenderer.cpp
+++ b/src/core/raster/qgsmultibandcolorrenderer.cpp
@@ -295,7 +295,7 @@ void QgsMultiBandColorRenderer::draw( QPainter* p, QgsRasterViewPort* viewPort,
           currentOpacity *= ( readValue( alphaData, transparencyType, currentRasterPos ) / 255.0 );
         }
 
-        if ( doubleNear( currentOpacity, 255 ) )
+        if ( doubleNear( currentOpacity, 1.0 ) )
         {
           imageScanLine[j] = qRgba( redVal, greenVal, blueVal, 255 );
         }
diff --git a/src/core/raster/qgssinglebandgrayrenderer.cpp b/src/core/raster/qgssinglebandgrayrenderer.cpp
index 7dc24dae625..bf0c0112664 100644
--- a/src/core/raster/qgssinglebandgrayrenderer.cpp
+++ b/src/core/raster/qgssinglebandgrayrenderer.cpp
@@ -149,7 +149,7 @@ void QgsSingleBandGrayRenderer::draw( QPainter* p, QgsRasterViewPort* viewPort,
           grayVal = 255 - grayVal;
         }
 
-        if ( doubleNear( currentAlpha, 255 ) )
+        if ( doubleNear( currentAlpha, 1.0 ) )
         {
           imageScanLine[j] = qRgba( grayVal, grayVal, grayVal, 255 );
         }