diff --git a/src/grammar/spark/SparkSql.g4 b/src/grammar/spark/SparkSql.g4
index bfe3791..ff9e0ba 100644
--- a/src/grammar/spark/SparkSql.g4
+++ b/src/grammar/spark/SparkSql.g4
@@ -1793,13 +1793,17 @@ BIGDECIMAL_LITERAL
     ;
 
 IDENTIFIER
-    : (LETTER | DIGIT | '_')+
+    : (LETTER | DIGIT | '_' | CUSTOM_VARS)+
     ;
 
 BACKQUOTED_IDENTIFIER
     : '`' ( ~'`' | '``' )* '`'
     ;
 
+CUSTOM_VARS
+    : '${'(IDENTIFIER)'}'
+    ;
+
 fragment DECIMAL_DIGITS
     : DIGIT+ '.' DIGIT*
     | '.' DIGIT+