diff --git a/dox/dev_guides/upgrade/upgrade.md b/dox/dev_guides/upgrade/upgrade.md
index 0a817715f7..122167d73d 100644
--- a/dox/dev_guides/upgrade/upgrade.md
+++ b/dox/dev_guides/upgrade/upgrade.md
@@ -247,6 +247,10 @@ The class *Select3D_Projector* now supports both orientation and projection tran
 
 Porting of user applications from an earlier OCCT version to version 6.9.0 requires taking into account the following major changes.
 
+@subsection upgrade_690_shaders 3D Viewer initialization
+
+3D Viewer now uses GLSL programs for managing frame buffer and stereoscopic output.
+For proper initialization, application should configure **CSF_ShadersDirectory** environment variable pointing to a folder with GLSL resources - files from folder **CASROOT**/src/Shaders.
 
 @subsection upgrade_690_selection Changes in Selection
 
diff --git a/src/Units/Units_Sentence.cxx b/src/Units/Units_Sentence.cxx
index bde82d5028..3969108813 100644
--- a/src/Units/Units_Sentence.cxx
+++ b/src/Units/Units_Sentence.cxx
@@ -60,7 +60,8 @@ Units_Sentence::Units_Sentence(const Handle(Units_Lexicon)& alexicon,
   
   thesequenceoftokens = new Units_TokensSequence();
   Handle(Units_TokensSequence) lstlexicon=alexicon->Sequence();
-  Units_NoSuchType_Raise_if(lstlexicon.IsNull(),"BAD LEXICON descriptor");
+  if(lstlexicon.IsNull())
+    Units_NoSuchType::Raise("BAD LEXICON descriptor");
   limchain=strlen(astring);
   i=0;