diff --git a/src/js/parser/javascript/grammar.peg b/src/js/parser/javascript/grammar.peg
index b77ece4..a4c739a 100644
--- a/src/js/parser/javascript/grammar.peg
+++ b/src/js/parser/javascript/grammar.peg
@@ -22,20 +22,20 @@ grammar JavascriptRegexp
                     / charset_literal <Literal>
   charset_escape <- "\\" esc:(
          code:[bdDfnrsStvwW] arg:""?
-       / code:"c" arg:.
+       / code:"c" arg:[a-zA-Z]
        / code:"0" arg:[0-7]+
        / code:"x" arg:( [0-9a-fA-F] [0-9a-fA-F] )
        / code:"u" arg:( [0-9a-fA-F] [0-9a-fA-F] [0-9a-fA-F] [0-9a-fA-F] )
        / code:"0" arg:""? )
-  charset_literal <- ( ""? literal:[^\\\]] ) / ( "\\" literal:. )
+  charset_literal <- ( ""? literal:[^\\\]] ) / ( literal:"\\" &"c" ) / ( "\\" literal:. )
   terminal <- "." <AnyCharacter>
             / escape <Escape>
             / literal <Literal>
   escape <- "\\" esc:(
          code:[bBdDfnrsStvwW1-9] arg:""?
-       / code:"c" arg:.
+       / code:"c" arg:[a-zA-Z]
        / code:"0" arg:[0-7]+
        / code:"x" arg:( [0-9a-fA-F] [0-9a-fA-F] )
        / code:"u" arg:( [0-9a-fA-F] [0-9a-fA-F] [0-9a-fA-F] [0-9a-fA-F] )
        / code:"0" arg:""? )
-  literal <- ( ""? literal:[^|\\/.\[\(\)?+*$^] ) / ( "\\" literal:. )
+  literal <- ( ""? literal:[^|\\/.\[\(\)?+*$^] ) / ( literal:"\\" &"c" ) / ( "\\" literal:. )