diff --git a/libkwineffects/kwinglutils.h b/libkwineffects/kwinglutils.h
--- a/libkwineffects/kwinglutils.h
+++ b/libkwineffects/kwinglutils.h
@@ -129,6 +129,7 @@
 
     enum Vec4Uniform {
         ModulationConstant,
+        TextureClamp,
         Vec4UniformCount
     };
 
@@ -186,6 +187,7 @@
     UniformColor     = (1 << 1),
     Modulate         = (1 << 2),
     AdjustSaturation = (1 << 3),
+    ClampTexture     = (1 << 4),
 };
 
 Q_DECLARE_FLAGS(ShaderTraits, ShaderTrait)
diff --git a/libkwineffects/kwinglutils.cpp b/libkwineffects/kwinglutils.cpp
--- a/libkwineffects/kwinglutils.cpp
+++ b/libkwineffects/kwinglutils.cpp
@@ -347,6 +347,7 @@
     mFloatLocation[Saturation]    = uniformLocation("saturation");
 
     mColorLocation[Color] = uniformLocation("geometryColor");
+    mVec4Location[TextureClamp] = uniformLocation("textureClamp");
 
     mLocationsResolved = true;
 }
@@ -877,22 +878,32 @@
     } else if (traits & ShaderTrait::UniformColor)
         stream << "uniform vec4 geometryColor;\n";
 
+    if (traits & ShaderTrait::ClampTexture) {
+        stream << "uniform vec4 textureClamp;\n";
+    }
+
     if (output != QByteArrayLiteral("gl_FragColor"))
         stream << "\nout vec4 " << output << ";\n";
 
     stream << "\nvoid main(void)\n{\n";
     if (traits & ShaderTrait::MapTexture) {
-        if (traits & (ShaderTrait::Modulate | ShaderTrait::AdjustSaturation)) {
-            stream << "    vec4 texel = " << textureLookup << "(sampler, texcoord0);\n";
+        stream << "vec2 texcoordC = texcoord0;\n";
 
+        if (traits & ShaderTrait::ClampTexture) {
+            stream << "texcoordC.x = clamp(texcoordC.x, textureClamp.x, textureClamp.z);\n";
+            stream << "texcoordC.y = clamp(texcoordC.y, textureClamp.y, textureClamp.w);\n";
+        }
+
+        if (traits & (ShaderTrait::Modulate | ShaderTrait::AdjustSaturation)) {
+            stream << "    vec4 texel = " << textureLookup << "(sampler, texcoordC);\n";
             if (traits & ShaderTrait::Modulate)
                 stream << "    texel *= modulation;\n";
             if (traits & ShaderTrait::AdjustSaturation)
                 stream << "    texel.rgb = mix(vec3(dot(texel.rgb, vec3(0.2126, 0.7152, 0.0722))), texel.rgb, saturation);\n";
 
             stream << "    " << output << " = texel;\n";
         } else {
-            stream << "    " << output << " = " << textureLookup << "(sampler, texcoord0);\n";
+            stream << "    " << output << " = " << textureLookup << "(sampler, texcoordC);\n";
         }
     } else if (traits & ShaderTrait::UniformColor)
         stream << "    " << output << " = geometryColor;\n";
diff --git a/plugins/scenes/opengl/scene_opengl.cpp b/plugins/scenes/opengl/scene_opengl.cpp
--- a/plugins/scenes/opengl/scene_opengl.cpp
+++ b/plugins/scenes/opengl/scene_opengl.cpp
@@ -1381,9 +1381,16 @@
     const QMatrix4x4 modelViewProjection = modelViewProjectionMatrix(mask, data);
     const QMatrix4x4 mvpMatrix = modelViewProjection * windowMatrix;
 
+
+    bool useX11TextureClamp = false;
+
     GLShader *shader = data.shader;
     if (!shader) {
         ShaderTraits traits = ShaderTrait::MapTexture;
+        if (kwinApp()->operationMode() == Application::OperationModeX11) {
+            useX11TextureClamp = true;
+            traits |= ShaderTrait::ClampTexture;
+        };
 
         if (data.opacity() != 1.0 || data.brightness() != 1.0 || data.crossFadeProgress() != 1.0)
             traits |= ShaderTrait::Modulate;
@@ -1506,6 +1513,25 @@
         nodes[i].texture->setWrapMode(GL_CLAMP_TO_EDGE);
         nodes[i].texture->bind();
 
+        if (i == ContentLeaf && useX11TextureClamp) {
+            // X11 windows are reparented to have their buffer in the middle of a larger texture
+            // holding the frame window.
+            // This code passes the texture geometry to the fragment shader
+            // any samples near the edge of the texture will be constrained to be
+            // at least half a pixel in bounds, meaning we don't bleed the transparent border
+            QRectF bufferContentRect = clientShape().boundingRect();
+            bufferContentRect.adjust(0.5, 0.5, -0.5, -0.5);
+            const QRect bufferGeometry = toplevel->bufferGeometry();
+
+            float leftClamp = bufferContentRect.left() / bufferGeometry.width();
+            float topClamp = bufferContentRect.top() / bufferGeometry.height();
+            float rightClamp = bufferContentRect.right() / bufferGeometry.width();
+            float bottomClamp = bufferContentRect.bottom() / bufferGeometry.height();
+            shader->setUniform(GLShader::TextureClamp, QVector4D({leftClamp, topClamp, rightClamp, bottomClamp}));
+        } else {
+            shader->setUniform(GLShader::TextureClamp, QVector4D({0, 0, 1, 1}));
+        }
+
         vbo->draw(region, primitiveType, nodes[i].firstVertex, nodes[i].vertexCount, m_hardwareClipping);
     }