diff --git a/effects/explosion/data/explosion.frag b/effects/explosion/data/explosion.frag
index 6cce152e8a..e0c8f8aa3d 100644
--- a/effects/explosion/data/explosion.frag
+++ b/effects/explosion/data/explosion.frag
@@ -3,8 +3,7 @@ uniform sampler2D startOffsetTexture;
 uniform sampler2D endOffsetTexture;
 uniform float factor;
 uniform float scale;
-uniform float textureWidth;
-uniform float textureHeight;
+uniform vec2 windowSize;
 
 const float regionTexSize = 512.0;
 
@@ -17,14 +16,14 @@ vec2 getOffset(sampler2D texture, vec2 pos)
 
 vec2 pix2tex( vec2 pix )
 {
-    return vec2( pix.s / textureWidth, pix.t / textureHeight );
+    return pix/windowSize;
 }
 
 void main()
 {
     // Original (unscaled) position in pixels
     // ### FIXME: Use a custom vertex shader that outputs the untransformed texcoords
-    vec2 origpos = varyingTexCoords * vec2(textureWidth, textureHeight);
+    vec2 origpos = varyingTexCoords * windowSize;
     // Position in pixels on the scaled window
     vec2 pos = origpos * scale;
     // Start/end position of current region
diff --git a/effects/explosion/explosion.cpp b/effects/explosion/explosion.cpp
index c148efaa74..75f56ac271 100644
--- a/effects/explosion/explosion.cpp
+++ b/effects/explosion/explosion.cpp
@@ -24,6 +24,7 @@ along with this program.  If not, see <http://www.gnu.org/licenses/>.
 #include <kwinglplatform.h>
 
 #include <QMatrix4x4>
+#include <QVector2D>
 
 #include <KStandardDirs>
 #include <kdebug.h>
@@ -152,6 +153,7 @@ void ExplosionEffect::paintWindow(EffectWindow* w, int mask, QRegion region, Win
         mShader->setUniform("screenTransformation", screenTransformation);
         mShader->setUniform("factor", (float)mWindows[w]);
         mShader->setUniform("scale", (float)scale);
+        mShader->setUniform("windowSize", QVector2D(w->width(), w->height()));
         glActiveTexture(GL_TEXTURE4);
         mStartOffsetTex->bind();
         glActiveTexture(GL_TEXTURE5);