diff --git a/Parser/ParModelica_Lexer.g b/Parser/ParModelica_Lexer.g
index 3eae7059f5c..4322e19e1f8 100644
--- a/Parser/ParModelica_Lexer.g
+++ b/Parser/ParModelica_Lexer.g
@@ -67,3 +67,5 @@ POWER_EW : '.^'; /* Modelica 3.0 */
 
 /* Modelica 3.1 */
 STREAM : 'stream'; /* for Modelica 3.1 stream connectors */
+IMPURE : 'impure'; /* for Modelica 3.3 impure functions */
+