diff --git a/docs/api/en/renderers/WebGLRenderer.html b/docs/api/en/renderers/WebGLRenderer.html
index e1a4b41a623129..fa43745a7f615c 100644
--- a/docs/api/en/renderers/WebGLRenderer.html
+++ b/docs/api/en/renderers/WebGLRenderer.html
@@ -30,7 +30,7 @@ <h3>[name]( [param:Object parameters] )</h3>
 
 		[page:WebGLRenderingContext context] - This can be used to attach the renderer to an existing
 	  [link:https://developer.mozilla.org/en-US/docs/Web/API/WebGLRenderingContext RenderingContext].
-		Default is null.<br />
+		Default is undefined.<br />
 
 		[page:String precision] - Shader precision. Can be *"highp"*, *"mediump"* or *"lowp"*.
 		Defaults to *"highp"* if supported by the device. See the note in "Things to Avoid"
diff --git a/src/renderers/WebGLRenderer.js b/src/renderers/WebGLRenderer.js
index 41eaf2716431ce..c3e95003edfe48 100644
--- a/src/renderers/WebGLRenderer.js
+++ b/src/renderers/WebGLRenderer.js
@@ -69,7 +69,7 @@ function WebGLRenderer( parameters = {} ) {
 
 	let _alpha;
 
-	if ( parameters.context !== undefined ) {
+	if ( _context !== null ) {
 
 		_alpha = _context.getContextAttributes().alpha;