diff --git a/common/gl_context_mgr.cpp b/common/gl_context_mgr.cpp
index af2863be36..125ed8fd11 100644
--- a/common/gl_context_mgr.cpp
+++ b/common/gl_context_mgr.cpp
@@ -2,6 +2,7 @@
  * This program source code file is part of KiCad, a free EDA CAD application.
  *
  * Copyright (C) 2016 CERN
+ * Copyright (C) 2017 KiCad Developers, see AUTHORS.txt for contributors.
  * @author Maciej Suminski <maciej.suminski@cern.ch>
  *
  * This program is free software; you can redistribute it and/or
@@ -78,7 +79,12 @@ void GL_CONTEXT_MANAGER::LockCtx( wxGLContext* aContext, wxGLCanvas* aCanvas )
     m_glCtxMutex.lock();
     wxGLCanvas* canvas = aCanvas ? aCanvas : m_glContexts.at( aContext );
 
-    canvas->SetCurrent( *aContext );
+    // Prevent assertion failure in wxGLContext::SetCurrent during GAL teardown
+    if( canvas->GetXWindow() )
+    {
+        canvas->SetCurrent( *aContext );
+    }
+
     m_glCtx = aContext;
 }