diff --git a/src/renderers/WebGLRenderer.js b/src/renderers/WebGLRenderer.js
index fb5f443c68c3ce..0d7162aa869475 100644
--- a/src/renderers/WebGLRenderer.js
+++ b/src/renderers/WebGLRenderer.js
@@ -436,14 +436,14 @@ function WebGLRenderer( parameters ) {
 
 	this.setViewport = function ( x, y, width, height ) {
 
-		_viewport.set( x, y, width, height )
+		_viewport.set( x, _height - y - height, width, height )
 		state.viewport( _currentViewport.copy( _viewport ).multiplyScalar( _pixelRatio ) );
 
 	};
 
 	this.setScissor = function ( x, y, width, height ) {
 
-		_scissor.set( x, y, width, height )
+		_scissor.set( x, _height - y - height, width, height )
 		state.scissor( _currentScissor.copy( _scissor ).multiplyScalar( _pixelRatio ) );
 
 	};
@@ -1082,7 +1082,7 @@ function WebGLRenderer( parameters ) {
 	// Rendering
 
 	this.render = function ( scene, camera, renderTarget, forceClear ) {
-		
+
 		if ( ! ( camera && camera.isCamera ) ) {
 
 			console.error( 'THREE.WebGLRenderer.render: camera is not an instance of THREE.Camera.' );