diff --git a/src/gui/kernel/qopenglcontext.cpp b/src/gui/kernel/qopenglcontext.cpp
index fb7d15c160..7ccdd7395b 100644
--- a/src/gui/kernel/qopenglcontext.cpp
+++ b/src/gui/kernel/qopenglcontext.cpp
@@ -578,6 +578,9 @@ bool QOpenGLContext::isValid() const
     without having to manage it manually.
 
     The context or a sharing context must be current.
+
+    The returned QOpenGLFunctions instance is ready to be used and it
+    does not need initializeOpenGLFunctions() to be called.
 */
 QOpenGLFunctions *QOpenGLContext::functions() const
 {