diff --git a/src/main/antlr/poliqarpplus/PoliqarpPlusLexer.g4 b/src/main/antlr/poliqarpplus/PoliqarpPlusLexer.g4
index 8648d87..b3bedb1 100644
--- a/src/main/antlr/poliqarpplus/PoliqarpPlusLexer.g4
+++ b/src/main/antlr/poliqarpplus/PoliqarpPlusLexer.g4
@@ -86,9 +86,13 @@
 EMPTYREL	: '@';
 
 /* Regular expressions and Regex queries */
-fragment RE_char     : ~('*' | '?' | '+' | '{' | '}' | '[' | ']'
-                     | '(' | ')' | '|' | '"' | ':' | '\'' | '\\');
+fragment RE_symbol     : ~('*' | '?' | '+' | '{' | '}' | '[' | ']'
+                     | '(' | ')' | '|' | '\\' | '"' | ':' | '\'');
+fragment RE_esc      : '\\' ('.' | '*' | '?' | '+' | '{' | '}' | '[' | ']'
+                     | '(' | ')' | '|' | '\\' | '"' | ':' | '\'');
+fragment RE_char     : (RE_symbol | RE_esc );
 fragment RE_alter    : ((RE_char | ('(' RE_expr ')') | RE_chgroup) '|' RE_expr )+;
+
 fragment RE_chgroup  : '[' RE_char+ ']';
 fragment RE_quant	 : (RE_star | RE_plus | RE_occ) QMARK?;
 fragment RE_opt      : (RE_char | RE_chgroup | ( '(' RE_expr ')')) '?';
diff --git a/src/main/antlr/poliqarpplus/PoliqarpPlusParser.g4 b/src/main/antlr/poliqarpplus/PoliqarpPlusParser.g4
index 1907773..571cf12 100644
--- a/src/main/antlr/poliqarpplus/PoliqarpPlusParser.g4
+++ b/src/main/antlr/poliqarpplus/PoliqarpPlusParser.g4
@@ -43,9 +43,9 @@
 ;
 
 key
-: WORD
+: (WORD
 | regex
-| NUMBER
+| NUMBER)
 ;
 
 foundry
@@ -149,7 +149,7 @@
 ;
 
 alignment
-: segment? (CARET segment)* CARET?
+: segment? ( (CARET segment)+ | CARET)
 ;
 
 disjunction