diff --git a/lanczosfilter.cpp b/lanczosfilter.cpp
index e6054b812f..9042c03415 100644
--- a/lanczosfilter.cpp
+++ b/lanczosfilter.cpp
@@ -33,6 +33,8 @@ along with this program.  If not, see <http://www.gnu.org/licenses/>.
 
 #include <kwineffects.h>
 
+#include <QFile>
+
 #include <qmath.h>
 #include <cmath>
 
@@ -45,7 +47,6 @@ LanczosFilter::LanczosFilter(QObject* parent)
     , m_offscreenTarget(0)
     , m_inited(false)
     , m_shader(0)
-    , m_uTexUnit(0)
     , m_uOffsets(0)
     , m_uKernel(0)
 {
@@ -84,13 +85,16 @@ void LanczosFilter::init()
         if (gl->isRadeon() && gl->chipClass() < R600)
             return;
     }
-    m_shader.reset(ShaderManager::instance()->loadFragmentShader(ShaderManager::SimpleShader,
-                                                                 gl->glslVersion() >= kVersionNumber(1, 40) ?
-                                                                 QStringLiteral(":/resources/shaders/1.40/lanczos-fragment.glsl") :
-                                                                 QStringLiteral(":/resources/shaders/1.10/lanczos-fragment.glsl")));
+    QFile ff(gl->glslVersion() >= kVersionNumber(1, 40) ?
+             QStringLiteral(":/resources/shaders/1.40/lanczos-fragment.glsl") :
+             QStringLiteral(":/resources/shaders/1.10/lanczos-fragment.glsl"));
+    if (!ff.open(QIODevice::ReadOnly)) {
+        qCDebug(KWIN_CORE) << "Failed to open lanczos shader";
+        return;
+    }
+    m_shader.reset(ShaderManager::instance()->generateCustomShader(ShaderTrait::MapTexture, QByteArray(), ff.readAll()));
     if (m_shader->isValid()) {
         ShaderBinder binder(m_shader.data());
-        m_uTexUnit    = m_shader->uniformLocation("texUnit");
         m_uKernel     = m_shader->uniformLocation("kernel");
         m_uOffsets    = m_shader->uniformLocation("offsets");
     } else {
@@ -251,6 +255,10 @@ void LanczosFilter::performPaint(EffectWindowImpl* w, int mask, QRegion region,
             updateOffscreenSurfaces();
             GLRenderTarget::pushRenderTarget(m_offscreenTarget);
 
+            QMatrix4x4 modelViewProjectionMatrix;
+            modelViewProjectionMatrix.ortho(0, m_offscreenTex->width(), m_offscreenTex->height(), 0 , 0, 65535);
+            thumbData.setProjectionMatrix(modelViewProjectionMatrix);
+
             glClearColor(0.0, 0.0, 0.0, 0.0);
             glClear(GL_COLOR_BUFFER_BIT);
             w->sceneWindow()->performPaint(mask, infiniteRegion(), thumbData);
@@ -270,6 +278,7 @@ void LanczosFilter::performPaint(EffectWindowImpl* w, int mask, QRegion region,
             createOffsets(kernelSize, sw, Qt::Horizontal);
 
             ShaderManager::instance()->pushShader(m_shader.data());
+            m_shader->setUniform(GLShader::ModelViewProjectionMatrix, modelViewProjectionMatrix);
             setUniforms();
 
             // Draw the window back into the FBO, this time scaled horizontally
@@ -408,7 +417,6 @@ void LanczosFilter::discardCacheTexture(EffectWindow *w)
 
 void LanczosFilter::setUniforms()
 {
-    glUniform1i(m_uTexUnit, 0);
     glUniform2fv(m_uOffsets, 16, (const GLfloat*)m_offsets);
     glUniform4fv(m_uKernel, 16, (const GLfloat*)m_kernel);
 }
diff --git a/lanczosfilter.h b/lanczosfilter.h
index 12a844ee8c..fff5cf28eb 100644
--- a/lanczosfilter.h
+++ b/lanczosfilter.h
@@ -65,7 +65,6 @@ private:
     QBasicTimer m_timer;
     bool m_inited;
     QScopedPointer<GLShader> m_shader;
-    int m_uTexUnit;
     int m_uOffsets;
     int m_uKernel;
     QVector2D m_offsets[16];
diff --git a/shaders/1.10/lanczos-fragment.glsl b/shaders/1.10/lanczos-fragment.glsl
index 3141d7907c..b6b135cdbb 100644
--- a/shaders/1.10/lanczos-fragment.glsl
+++ b/shaders/1.10/lanczos-fragment.glsl
@@ -1,15 +1,15 @@
-uniform sampler2D texUnit;
+uniform sampler2D sampler;
 uniform vec2 offsets[16];
 uniform vec4 kernel[16];
 
-varying vec2 varyingTexCoords;
+varying vec2 texcoord0;
 
 void main(void)
 {
-    vec4 sum = texture2D(texUnit, varyingTexCoords.st) * kernel[0];
+    vec4 sum = texture2D(sampler, texcoord0.st) * kernel[0];
     for (int i = 1; i < 16; i++) {
-        sum += texture2D(texUnit, varyingTexCoords.st - offsets[i]) * kernel[i];
-        sum += texture2D(texUnit, varyingTexCoords.st + offsets[i]) * kernel[i];
+        sum += texture2D(sampler, texcoord0.st - offsets[i]) * kernel[i];
+        sum += texture2D(sampler, texcoord0.st + offsets[i]) * kernel[i];
     }
     gl_FragColor = sum;
 }
diff --git a/shaders/1.40/lanczos-fragment.glsl b/shaders/1.40/lanczos-fragment.glsl
index 0852ea1028..a77d560674 100644
--- a/shaders/1.40/lanczos-fragment.glsl
+++ b/shaders/1.40/lanczos-fragment.glsl
@@ -1,18 +1,18 @@
 #version 140
 
-uniform sampler2D texUnit;
+uniform sampler2D sampler;
 uniform vec2 offsets[16];
 uniform vec4 kernel[16];
 
-in vec2 varyingTexCoords;
+in vec2 texcoord0;
 out vec4 fragColor;
 
 void main(void)
 {
-    vec4 sum = texture(texUnit, varyingTexCoords.st) * kernel[0];
+    vec4 sum = texture(sampler, texcoord0.st) * kernel[0];
     for (int i = 1; i < 16; i++) {
-        sum += texture(texUnit, varyingTexCoords.st - offsets[i]) * kernel[i];
-        sum += texture(texUnit, varyingTexCoords.st + offsets[i]) * kernel[i];
+        sum += texture(sampler, texcoord0.st - offsets[i]) * kernel[i];
+        sum += texture(sampler, texcoord0.st + offsets[i]) * kernel[i];
     }
     fragColor = sum;
 }